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Breytenbach, I. J. "The relationship between index testing and California Bearing Ratio values for natural road construction materials in South Africa." Pretoria : [s.n.], 2009. http://upetd.up.ac.za/thesis/available/etd-12152009-144255.
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Karagania, Richard M. "Road roughness and infrastructure damage." Thesis, Queensland University of Technology, 1997. https://eprints.qut.edu.au/36011/1/36011_Karagania_1997.pdf.
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Scientific research has identified road roughness as a significant factor that
contributes to increased vehicle dynamic wheel loads and therefore damage to
pavements and bridges. The other factors include vehicle speed and vehicle
suspension type. More specifically and regarding road roughness, research has
shown that damaging effects are caused by certain wavelengths and features in road
profiles and not the overall road roughness. Various methods of classifying road
roughness based on the ride quality are available. These methods, though important,
are limited in identifying the location of features along road profiles that cause
exceptionally high dynamic wheel loads hence damage. It is the development of a
methodology for identifying the location of these abnormally high dynamic wheel
forces that this thesis addresses.
A vehicle-road interaction model was developed for this research. This computer
model uses a quarter vehicle model and recorded road profile elevation data to
simulate the response of half a vehicle axle (quarter vehicle) driving along a road. 47
road profiles over 17 bridges were measured to run the model.
Signal processing techniques developed by electrical and mechanical engineers have
been used as an additional tool to road profile analysis. These techniques are very
powerful and their application to road profile investigations is significant. Using
computer simulation and by combining ride and damage criteria analysis, a
methodology of identifying segments of road that induce high dynamic wheel forces
and the location of abnormally high dynamic wheel forces has been established.
3
Mikesell, David Russell. "Portable automated driver for universal road vehicle dynamics testing." Columbus, Ohio : Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1198722243.
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Giudici, Henri. "Frost heave testing of norwegian materials for road infrastructure." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amslaurea.unibo.it/7590/.
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In areas of seasonal frost, frost susceptibility composed by frost heaving during the winter and thaw softening during the spring is one of the most dangerous phenomenon for transportation, road and railway infrastructure. Therefore, the need for frost protection layer becomes imperative. The purpose of frost protection layer is to prevent frost from penetrating down through the pavement and into the sub-soils. Frost susceptible soils under the road can be cause damages on the roads or other structures due to frost heave or reduced capacity characteristics thaw period.
"Frost heave" is the term given to the upwards displacement of the ground surface caused by the formation of ice within soils or aggregates (Rempel et al., 2004). Nowadays in Scandinavia the most common material used in frost protection layer in the pavement structure of roads and in the ballast of the railway tracks are coarse-grain crushed rocks aggregates. Based on the capillary rise, the mechanics of frost heave phenomenon is based on the interaction between aggregates and water, as suggested by Konrad and Lemieux in 2005 that said that the fraction of material below the 0.063 mm sieve for coarse-grained soils must be controlled so as to reduce the sensitivity to frost heave. The study conducted in this thesis project is divided in two parts:
- the analysis of the coarse grained aggregates used in frost protection layer in Norway;
- the analysis of the frost heave phenomenon in the laboratory under known boundary conditions, through the use of the most widely used method, the frost heave test, in” closed system” (without access of water).
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Motamedi, Mohammad. "Road Surface Measurement and Multi-Scale Modeling of Rubber Road Contact and Adhesion." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/76733.
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A major challenge in tire, as well as in road engineering, is to understand the intricate mechanisms of friction. Pavement texture is a feature of the road surface that determines most tire-road interactions, and can be grouped into two classes: macro-texture, resulting mainly in the hysteretic component of friction, and micro-texture, resulting in adhesion. If both textures are maintained at high levels, they can help provide sufficient resistance to skidding.
The ultimate objective of this research is to develop a physics-based multiscale rubber-road friction model that can predict the effectiveness of the tire as it interacts with the vehicle and the pavement. The model is developed based on sound physics and contact mechanics theories and uses road profile measurements and data measured on various tire compounds.
To be able to predict road surface characteristics, it is proven that road surfaces are of fractal nature on given ranges of scale. It is shown that while global fractal quantities fail to classify pavement profiles, a local fractal parameter and three other texture parameters can separate road profiles that have different friction characteristics.
Through the implementation of various contact theories and by conducting simulation studies, a methodical understanding of contact mechanics and of the effect of the diverse factors that influence friction is attained. To predict the viscoelastic friction between any given tire tread compound and road, the Nanovea JR25 portable optical profilometer is used to measure the road profiles. To characterize the road profile, the one-dimensional pavement measurements are used to obtain the two-dimensional power spectrum, followed by testing and characterizing the tread compounds (this is being carried out by Bridgestone). This data is used to develop a comprehensive analytical methodology to predict friction. To validate this model, a Dynamic Friction Test apparatus is designed and built. The friction tester enables measurement of the friction between tread compound samples and arbitrary surfaces, at different slip ratios. The correlations between the simulations and both indoor and outdoor experimental results are investigated.Ph. D.
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Lambert, John Peter. "Novel assessment test for granular road foundation materials." Thesis, Loughborough University, 2007. https://dspace.lboro.ac.uk/2134/3099.
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Drivers for sustainability have made it necessary for the construction industry to adapt its traditional processes to become both more efficient and produce less waste. Performance based design and specification in the UK for motorways and trunk roads permits a very flexible approach to pavement design, material selection and performance related testing aimed at utilising materials to their maximum potential. However, it is clear that within the emerging philosophy of using materials that are 'fit for purpose' there are many technical challenges for design and specification. There is a need to develop suitable methods of evaluating materials prior to their being used on site. This project was born out of this requirement, with a particular emphasis on coarse granular materials due to their common role in capping construction and also their unique difficulty for measurement under laboratory conditions due to their large range of particle size. A novel assessment test for coarse capping materials for roads that can be used to indicate their likely short-term in situ performance, under controlled laboratory conditions before construction on site, has been developed during this research programme. Key findings relating to the behaviour of coarse capping materials, the use of stiffness measuring devices and variables that influence the measurement of composite stiffness are discussed in detail. The research highlights the necessity for adequate drainage and protection of foundation materials against increase in water content. When adopting a performance specification the timing of the pavement assessment is critical, both on site and in the laboratory. The performance measured on site should perhaps only be considered as a 'snapshot' relating to the stress state in the material at the time of testing.
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Adams, Jordan. "The feasibility of a road vehicle mounted aerodynamic testing apparatus." Master's thesis, University of Cape Town, 2011. http://hdl.handle.net/11427/10004.
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A ground vehicle mounted aerodynamic testing apparatus has been identified as a candidate concept for a low-cost alternative to traditional techniques. This dissertation explores the feasibility of a ground vehicle based system by identifying physical and practical issues facing such a system. The focus is on the two most important physical problems facing the concept. These are: the ride dynamics of a vehicle as it traverses a road, and the extent of the distortion of the airflow around a vehicle. Each of these problems is quantified using approximate methods in order to estimate their influence on the testing of the aircraft in order to determine if the concept is workable.
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Moynahan, Nathan A. "Development of a vehicle road load model for ECU broadcast power verification in on-road emissions testing." Morgantown, W. Va. : [West Virginia University Libraries], 2005. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4454.
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Thesis (M.S.)--West Virginia University, 2005.Title from document title page. Document formatted into pages; contains xi, 117 p. : ill. (some col.), col. map. Includes abstract. Includes bibliographical references (p. 75-77).
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Jamtsho, Lungten. "Performance load testing and structural adequacy evaluation of road bridge decks." Thesis, Queensland University of Technology, 2011. https://eprints.qut.edu.au/46822/1/Lungten_Jamtsho_Thesis.pdf.
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Many ageing road bridges, particularly timber bridges, require urgent improvement due to the demand imposed by the recent version of the Australian bridge loading code, AS 5100. As traffic volume plays a key role in the decision of budget allocations for bridge refurbishment/ replacement, many bridges in low volume traffic network remain in poor condition with axle load and/ or speed restrictions, thus disadvantaging many rural communities. This thesis examines an economical and environmentally sensible option of incorporating disused flat rail wagons (FRW) in the construction of bridges in low volume, high axle load road network. The constructability, economy and structural adequacy of the FRW road bridge is reported in the thesis with particular focus of a demonstration bridge commissioned in regional Queensland. The demonstration bridge comprises of a reinforced concrete slab (RCS) pavement resting on two FRWs with custom designed connection brackets at regular intervals along the span of the bridge. The FRW-RC bridge deck assembly is supported on elastomeric rubber pads resting on the abutment. As this type of bridge replacement technology is new and its structural design is not covered in the design standards, the in-service structural performance of the FRW bridge subjected to the high axle loadings prescribed in AS 5100 is examined through performance load testing. Both the static and the moving load tests are carried out using a fully laden commonly available three-axle tandem truck. The bridge deck is extensively strain gauged and displacement at several key locations is measured using linear variable displacement transducers (LVDTs). A high speed camera is used in the performance test and the digital image data are analysed using proprietary software to capture the locations of the wheel positions on the bridge span accurately. The wheel location is thus synchronised with the displacement and strain time series to infer the structural response of the FRW bridge. Field test data are used to calibrate a grillage model, developed for further analysis of the FRW bridge to various sets of high axle loads stipulated in the bridge design standard. Bridge behaviour predicted by the grillage model has exemplified that the live load stresses of the FRW bridge is significantly lower than the yield strength of steel and the deflections are well below the serviceability limit state set out in AS 5100. Based on the results reported in this thesis, it is concluded that the disused FRWs are competent to resist high axle loading prescribed in AS 5100 and are a viable alternative structural solution of bridge deck in the context of the low volume road networks.
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Penk, Mildred Lotus. "Mental Imagery: The Road to Construct Validity." Thesis, University of North Texas, 1988. https://digital.library.unt.edu/ark:/67531/metadc331872/.
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Internal consistency reliability and validity were established for a new 31 item Imagery Manipulation Scale. Previous attempts to correlate subjectively rated control of visual imagery with tests of spatial ability have been unsuccessful. However, no attempt to construct a subjectively rated control of imagery scale was located which tried to establish internal consistency reliability and both content and construct validity. Further, no research was located in which subjects were requested to rate their imagery ability utilized during the performance of the actual spatial tasks used to try to establish validity. A new scale of subjectively rated control of imagery was devised in which subjects were requested to rate their imagery while solving spatial tasks which involved visualizing the manipulation of geometric forms. Content validity was established by analyzing the transformation involved while solving the spatial problems. Internal consistency reliability for the 31 item scale was established across two samples. Validity was established with the second sample (100 university students: 26 male and 74 female). The task utilized to provide validity could be objectively scored, and was made up of four spatial subtests, which were adapted from the Vandenberg and Kuse Mental Rotations Test, the Kosslyn Directions Test, performed in both the forward and backward direction, and a block task utilized by Snyder. A convergent and discriminant validity analysis established construct validity. Further, the hypotheses of three investigators, Kosslyn, Shepard and his colleagues, and Snyder, were supported by the results of the present investigation, thus substantiating the conclusion that reported control of imagery processing can be operationalized with performance scores on spatial ability tasks.
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Lynch, Alan Gerald. "Trends in back-calculated stiffness of in-situ recycled and stabilised road pavement materials." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/85857.
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Thesis (MEng)-- Stellenbosch University, 2013.ENGLISH ABSTRACT: Two common methods of road pavement, granular material stabilisation used in road construction throughout South Africa today include Cold in Place Recycling (CIPR) and stabilisation with cement or bitumen and an active filler to create Bitumen Stabilised Materials (BSM). As part of the updating of the South African Pavement Design Method (SAPDM) an experimental section, investigating the structural capacity of cement and lime stabilised and BSM pavement layers, was constructed and will be monitored over a two year period. As part of this study Falling Weight Deflectometer (FWD) measurements were taken on the various experimental stabilised pavement layers constructed. The FWD deflection data, measured at various time intervals over a 360 day period, forms the basis of the study presented here. The objective of this thesis was to identify typical back-calculated layer stiffnesses and their variability over time for the various in-situ recycled and stabilised base layers constructed within the experimental section. Stabiliser type, content and layer thicknesses were varied across experimental sub-sections. Trends in back-calculated stiffness of cement stabilised base layers consistently showed significant reductions in layer stiffness subsequent to construction traffic loading. Subsequent to the initial reduction in stiffness little change in stiffness was noted under normal traffic loads. Observations on the trends in back-calculated stabilised layer stiffness per material type over time indicated that seasonal moisture and temperature fluctuations have an effect on the stiffness of the pavement structure as a whole. BSM materials showed significant variability over time in-line with seasonal variability in the supporting subgrade stiffness in the southbound lane. BSM materials with 1% cement added in the northbound lane show initial stiffness reductions due to direct rainfall application however a significant increase in layer stiffness occurs up to 360 days after construction. BSMs with 2% cement in the northbound lane show significant increases in layer stiffness over the 360 day observation period. No significant difference in stiffness trend was observed between BSM emulsion a BSM foam materials. The BSM emulsion with 0.9% residual bitumen and 1% cement was observed to show rapid reduction in stiffness upon opening to traffic and reverting to stiffness values similar to an unbound material of approximately 350 MPa. Cement and lime stabilised materials showed typical post 28 –day average stiffnesses per sub-section ranging between 600 MPa and 1800 MPa. BSM foam with 1% cement added were observed to have average stiffnesses per sub-section in the range of 400MPa to 2200 MPa and BSM emulsion with 1% cement with stiffnesses between 400 MPa to 1700 MPa over the 360 day period. BSMs with 2% cement added showed stiffness ranges between 900 MPa to 4300 MPa for BSM foam and 900 MPa to 3900 MPa for BSM emulsions over the 360 day period. The spatial variability of back-calculated stiffness per sub-section of a particular stabilisation design was significant and was observed, through the Co-efficient of Variation (COV), to increase over time. The effect of the observed variability when incorporated into a pavement design scenario, requiring a design reliability of 90%, showed 50% of the pavement structure would be overdesigned by a factor of 4. With respect to the current philosophies on the development of stiffness over time of cement and lime stabilised and BSM pavement layers some useful observations were made. Cement stabilised materials correlate well with stiffness development theories predicted by previous studies. Theories relating to the stiffness development of BSMs however did not predict the levels of variability in base layer stiffness observed on the experimental section. The continued observation of the experimental section for another year will give greater insight to the stiffness trends of the stabilised materials discussed above.
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Avenell, Gordon Kenneth. "Road Testing Robinson et al (2009) - Does the “theory” work in practice?" Thesis, Griffith University, 2015. http://hdl.handle.net/10072/366760.
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School leaders matter for school success. Recognition of the importance of school leadership has led to increased emphasis on instructional leadership, however, while broad agreement exists on the importance, there is less consensus on what aspects of instructional leadership maximise best opportunity for student learning.
Several researchers in the last decade have distilled a summary of optimum leadership behaviours from research, across which there is much similarity. The most significant of these distillations is that of Robinson, Hohepa, and Lloyd (2009) who conducted the Best Evidence Synthesis (BES).
This study is unique in that whilst the leadership behaviours of the BES are pre-eminent in research theory, they had not been previously tested in practice. There is abundant theory, but does the theory work in practice?
Using the lens of Robinson et al. (2009) and six leadership dimensions drawn from their BES, this study across 127 schools and 1,612 teaching staff in a Catholic Education system located in Queensland used a mixed methods approach to examine the relationship between these leadership behaviours and school performance.
This study identified the presence of these leadership behaviours and established a direct relationship with student outcomes. Further, this research significantly elaborates on the specific instructional leadership behaviours for school leaders to successfully enhance student learning outcomes and identifies contemporary specific actions school leaders may employ to maximise student learning through teacher efficacy.
This research indicates the instructional leadership dimensions, drawn from Robinson et al.’s (2009) BES meta-analysis of direct evidence from 27 international quantitative studies, are applicable within the Australian Catholic context despite no Australian instructional leadership studies being included in that analysis.Thesis (Professional Doctorate)
Doctor of Education (EdD)
School of Education and Professional Studies
Arts, Education and Law
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De, Guzman Earl Marvin. "Road Embankments on Seasonally-Frozen Peat Foundations." Canadian Geotechnical Society - Proceedings of the 67th Canadian Geotechnical Conference, 2013. http://hdl.handle.net/1993/30306.
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Muskeg or peat deposits cover large areas in northern Manitoba. Test sections of a newly constructed highway on peat were instrumented to investigate their performance and to develop more economical means of construction method. Test Section ‘A’ was constructed with geotextile base layer while Section ‘B’ was with geotextile and corduroys (timber logs). The test sections were constructed during winter for ease in mobilizing construction equipment at the site when the ground was frozen and were instrumented to observe its behaviour and performance. Settlements were measured using monitoring plates and pins. Ground temperatures were measured using thermistors. Porewater pressures were measured using vibrating wire piezometers.
Peat in the study area has an average thickness of 4m, with the upper layer classified as fibrous and the lower layer as amorphous with strong to complete decomposition. Standard laboratory tests were conducted on bored samples from the site. Hydraulic conductivity tests were carried out at different vertical pressures to determine its permeability. Thermal conductivity was determined at frozen and unfrozen state of peat. Conventional incremental oedometer tests were conducted to determine the compressibility parameters and secondary compression indices of the peat layers. Constant-rate-of-strain (CRS) tests were also performed to supplement the results obtained from the conventional method. Isotropically-Consolidated Undrained (CIŪ) triaxial tests were carried out to determine the shear strength of peat.
A commercially-available computer program was used in the numerical modelling to simulate the field performance of the instrumented sections. The results from numerical modelling were reasonably close to the measured values in the field. Laboratory-scale physical modelling was undertaken to understand further the operating mechanisms involved in the performance of the two test sections under a more controlled environment. Artificial transparent clay that has similar deformation properties with most of the natural clays and peats was used as foundation material. It allows determination of spatial deformations beneath the embankment using Particle Image Velocimetry (PIV) technique. The load-settlement behaviour in the field was also reasonably simulated in the laboratory-scaled physical model. Deformation patterns from PIV indicate that embankment with geotextile layer and corduroy has smaller settlements and lateral movements in the foundation compared to that of the embankment with only geotextile layer.
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Borén, Sven. "Sustainable Personal Road Transport : The Role of Electric Vehicles." Licentiate thesis, Blekinge Tekniska Högskola, Institutionen för strategisk hållbar utveckling, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-11715.
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Electric vehicles can play an important role in a future sustainable road transport system and many Swedish politicians would like to see them implemented faster. This is likely desirable to reach the target of a fossil independent vehicle fleet in Sweden by 2030 and a greenhouse gas neutral Swedish society no later than 2050. However, to reach both these targets, and certainly to support the full scope of sustainability, it is important to consider the whole life-cycle of the vehicles and also the interaction between the transport sector and other sectors. So far, there are no plans for transitions towards a sustainable transport system applying a sufficiently wide systems perspective, in Sweden or elsewhere. This implies a great risk for sub-optimizations. The overall aim of this work is to elaborate methodological support for development of sustainable personal road transport systems that is informed by a strategic sustainable development perspective. The Framework for Strategic Sustainable Development (FSSD) is used as a foundation for the work to ensure a sufficiently wide systems perspective and coordinated collaboration across disciplines and sectors, both in the research and application. Maxwell’s Qualitative Research Design and the Design Research Methodology are used as overall guides for the research approach. Specific research methods and techniques include literature studies, action research seminars, interviews, and measurements of energy use, costs, and noise. Moreover, a case study on the conditions for a breakthrough for vehicles in southeast Sweden has been used as a test and development platform. Specific results include a preliminary vision for electrical vehicles in southeast Sweden, framed by the principled sustainability definition of the FSSD, an assessment of the current reality in relation to that vision, and proposed solutions to bridge the gap, organized into a preliminary roadmap. The studies show that electric vehicles have several sustainability advantages even when their whole life-cycle is considered, provided that they are charged with electricity from new renewable sources. Electrical vehicles also imply a low total cost of ownership and could promote new local ‘green jobs’ under certain conditions. Particularly promising results are seen for electric buses in public transport. As a general result, partly based on the experiences from the specific case, a generic community planning process model is proposed and its usefulness for sustainable transport system development is discussed. The strategic sustainable development perspective of this thesis broadens the analysis beyond the more common focus on climate change issues and reduces the risk of sub-optimizations in community and transport system development. The generic support for multi-stakeholder collaboration could potentially also promote a more participatory democratic approach to community development, grounded in a scientific foundation. Future research will explore specific decision support systems for sustainable transport development based on the generic planning process model.GreenCharge
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Singh, Yuvraj. "Regression Models to Predict Coastdown Road Load for Various Vehicle Types." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1595265184541326.
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Rösth, Marcus. "Hydraulic Power Steering System Design in Road Vehicles : Analysis, Testing and Enhanced Functionality." Doctoral thesis, Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-8186.
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Demands for including more functions such as haptic guiding in power steering systems in road vehicles have increased with requirements on new active safety and comfort systems. Active safety systems, which have been proven to have a positive effect on overall vehicle safety, refer to systems that give the driver assistance in more and less critical situations to avoid accidents. Active safety features are going to play an increasingly important roll in future safety strategies; therefore, it is essential that sub systems in road vehicles, such as power steering systems, are adjusted to meet new demands. The traditional Hydraulic Power Assisted Steering, HPAS, system, cannot meet these new demands, due to the control unit's pure hydro-mechanical solution. The Active Pinion concept presented in this thesis is a novel concept for controlling the steering wheel torque in future active safety and comfort applications. The concept, which can be seen as a modular add-on added to a traditional HPAS system, introduces an additional degree of freedom to the control unit. Different control modes used to meet the demands of new functionality applications are presented and tested in a hardware-in-the-loop test rig. This thesis also covers various aspects of hydraulic power assisted steering systems in road vehicles. Power steering is viewed as a dynamic system and is investigated with linear and non-linear modeling techniques. The valve design in terms of area gradient is essential for the function of the HPAS system; therefore, a method involving optimization has been developed to determine the valve characteristic. The method uses static measurements as a base for calculation and optimization; the results are used in both linear and the non-linear models. With the help of the linear model, relevant transfer functions and the underlying control structure of the power steering system have been derived and analyzed. The non-linear model has been used in concept validation of the Active Pinion. Apart from concept validation and controller design of the active pinion, the models have been roven effective to explain dynamic phenomena related to HPAS systems, such as the chattering phenomena and hydraulic lag.The printed version and the electronic version differ in that the electronic version contains two built in video films (see page 78 and page 89).
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Rösth, Marcus. "Hydraulic power steering system design in road vehicles : analysis, testing and enhanced functionality /." Linköping : Division of Fluid and Mechanical Engineering Systems, Department of Mechanical Engineering, Linköping University, 2007. http://www.bibl.liu.se/liupubl/disp/disp2007/tek1068s.pdf.
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Abidin, Mohd Azman Zainul. "Vehicle ride under transient conditions using combined on-road testing and numerical analysis." Thesis, Loughborough University, 2005. https://dspace.lboro.ac.uk/2134/15309.
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The thesis outlines a hierarchical modelling methodology for investigation in vehicle dynamics, in particular for combined ride and handling manoeuvres. The methodology involves the use of detailed multi-degrees of freedom models of vehicles with the inclusion of sources of non-linearity, using a multi-body approach, based on Lagrangian dynamics for constrained systems. It also includes the use of simpler and task-specific models, formulated in Newton-Euler approach. These simpler models with lower degrees of freedom, but with appropriate level of detail are more efficient in the study of specific, but non-trivial problems such as transient behaviour of vehicles in combined ride and handling, as encountered in many routine daily manoeuvres. The modelling methodology is supported by careful vehicle testing, both for validation of the proposed approach, and assessment of the extent of applicability of simple, intermediate and multi-degrees of freedom full-vehicle models. Certain important vehicle handling and ride characteristics in pitch plane dynamics, roll behaviour, vehicle body bounce and combination of these have been studied, as well as the effectiveness of restraining action of chassis elements, such as the semileading and trailing arms for passive control of vehicle squat and dive motions, arising from acceleration from coast to drive and deceleration/brake of vehicle from drive to coast. Combined pitch and bounce motions have been studied when negotiating speed traps such as bumps, which also combine with significant body roll when single event obstacles of this kind are introduced. The novelty of the research is in the detailed integrative numerical-experimental approach, and the development of intermediate models that adequately predict vehicle behaviour under steady and non-steady conditions for a wide range of ride and handling manoeuvres. The investigations have culminated in a significant number of findings of practical use, particularly the ineffectiveness of anti-squat and dive features when combined pitch and bounce motions limit the usefulness of these devices. On the contrary, excessive roll dynamic behaviour of the vehicle is effectively palliated by the anti-roll bar, even under complex combined pitch, roll and body bounce such as those experienced in negotiating single event speed bumps. Good agreement is found between the predictions of the intermediate model and those of the multi-body model and the actual vehicle tests, particularly for pitch and bounce dynamics.
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Nitsche, Philippe. "Safety-critical scenarios and virtual testing procedures for automated cars at road intersections." Thesis, Loughborough University, 2018. https://dspace.lboro.ac.uk/2134/34433.
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This thesis addresses the problem of road intersection safety with regard to a mixed population of automated vehicles and non-automated road users. The work derives and evaluates safety-critical scenarios at road junctions, which can pose a particular safety problem involving automated cars. A simulation and evaluation framework for car-to-car accidents is presented and demonstrated, which allows examining the safety performance of automated driving systems within those scenarios. Given the recent advancements in automated driving functions, one of the main challenges is safe and efficient operation in complex traffic situations such as road junctions. There is a need for comprehensive testing, either in virtual testing environments or on real-world test tracks. Since it is unrealistic to cover all possible combinations of traffic situations and environment conditions, the challenge is to find the key driving situations to be evaluated at junctions. Against this background, a novel method to derive critical pre-crash scenarios from historical car accident data is presented. It employs k-medoids to cluster historical junction crash data into distinct partitions and then applies the association rules algorithm to each cluster to specify the driving scenarios in more detail. The dataset used consists of 1,056 junction crashes in the UK, which were exported from the in-depth On-the-Spot database. The study resulted in thirteen crash clusters for T-junctions, and six crash clusters for crossroads. Association rules revealed common crash characteristics, which were the basis for the scenario descriptions. As a follow-up to the scenario generation, the thesis further presents a novel, modular framework to transfer the derived collision scenarios to a sub-microscopic traffic simulation environment. The software CarMaker is used with MATLAB/Simulink to simulate realistic models of vehicles, sensors and road environments and is combined with an advanced Monte Carlo method to obtain a representative set of parameter combinations. The analysis of different safety performance indicators computed from the simulation outputs reveals collision and near-miss probabilities for selected scenarios. The usefulness and applicability of the simulation and evaluation framework is demonstrated for a selected junction scenario, where the safety performance of different in-vehicle collision avoidance systems is studied. The results show that the number of collisions and conflicts were reduced to a tenth when adding a crossing and turning assistant to a basic forward collision avoidance system. Due to its modular architecture, the presented framework can be adapted to the individual needs of future users and may be enhanced with customised simulation models. Ultimately, the thesis leads to more efficient workflows when virtually testing automated driving at intersections, as a complement to field operational tests on public roads.
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Clark, Bradley. "The physiology of road cycling : New testing and training methodologies for competitive cyclists." Thesis, Federation University Australia, 2014. http://researchonline.federation.edu.au/vital/access/HandleResolver/1959.17/81592.
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Objective: The objective of this project is to describe and test the efficacy of new testing and training techniques for competitive cyclists. Methods: Physiological variables and cycling performance were measured during a graded exercise test (GXT) and a novel, computer-simulated, variable gradient 20-km cycling time-trial. Initially, data collected from the time-trial and GXT were used to establish the reliability of the time-trial, determine the laboratory correlates of hilly cycling performance and examine the pacing pattern during hilly cycling performance. Then, results from a series of GXT’s and time-trials were used to establish the effects of a brief period of overload training on the physiology and performance of competitive cyclists. Results: Power output and performance time measured during a computer simulated 20-km variable gradient cycling test were reliable, however reliability diminished with increasing time between trials. Performance in variable gradient time-trial correlated strongly with absolute measures of physiological variables; however the strength of correlations increased when variables were measured relative to body mass. Power output was highest during the first four and last two kilometres of a variable gradient time-trial. Additionally, there were large differences in power output between consecutive one kilometre segments throughout the trial, particularly when the difference in gradient between segments was greater. Performance in the variable gradient time-trial improved substantially following a brief period of overload training. Performance improvement corresponded with adaptation in important physiological determinants of cycling performance, namely maximal oxygen uptake, lactate threshold and gross efficiency. Conclusions: Variable gradient, cycling time-trial tests can be used to detect meaningful changes in performance, evoke dynamic distribution of power output and are best suited to cyclists who produce high power outputs relative to body mass. The current project also determined that a brief period of overload training induces physiological adaptation and substantial improvement in cycling performance in competitive cyclists. Sport scientists, coaches and cyclists can use this information to determine the testing and training techniques used in preparation for competition.Doctor of Philosophy
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Baxter-Gilbert, James H. "The Long Road Ahead: Understanding Road-related Threats to Reptiles and Testing if Current Mitigation Measures are Effective at Minimizing Impacts." Thesis, Laurentian University of Sudbury, 2014. https://zone.biblio.laurentian.ca/dspace/handle/10219/2137.
Full textAbstract:
Reptile populations are suffering substantial global losses and roads are identified as one of the leading threats to their persistence. Currently, efforts to mitigate this threat are being implemented with various levels of success. I studied the effectiveness of exclusion structures (i.e., fencing) at preventing reptiles from gaining access to the road, and reducing road mortality. I also examined if population connectivity structures (i.e., ecopassages) were effective at reducing habitat and population fragmentation and allowing individuals to access habitats, resources, and mates on both sides of a major road (4 lane highway). I found that the fence was ineffective at preventing reptiles from gaining access to the road; however, reptiles were observed using the ecopassages to cross the road. Behavioural trials testing painted turtles’ (Chrysemys picta) willingness to use an ecopassage demonstrated that refusal was twice more likely than use of an ecopassage. I also examined the potential for roads to pose a physiological threat to roadside populations of reptiles by examining corticosterone (CORT), a stress hormone linked to negative health effects in cases of elevated levels over the long-term. To assess if individuals living near a major road had higher CORT levels than individuals from a less impacted population, I developed a novel means of measuring CORT from painted turtle claws in partnership with Dr. Gabriela Mastromonaco (Toronto Zoo). With long-term CORT levels considered as a proxy for chronic physiological stress, I did not find evidence that populations near roads had altered stress levels. However, this seminal study will provide the framework for further examination of more species, including species-at-risk, and a better understanding of effects of anthropogenic environments on wildlife health. As road ecologists strive to expand our understanding of the threats roads pose to reptiles, it is important that this field spans multiple disciplines, so that we can both understand the direct and indirect threats that roads cause and develop effective mitigation that preserves biodiversity within our anthropogenic landscape.
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Yaiaroon, Niphan. "Probabilistic modelling of extreme traffic load-effects based on WIM data." Thesis, The University of Sydney, 2009. https://hdl.handle.net/2123/28224.
Full textAbstract:
The primary aims of this thesis are to develop a realistic probabilistic model of extreme
traffic load-effects (referred to as a Probabilistic Model), which could be used for a
reliability—based assessment of the safety of existing bridges, and to develop a model
that provides an efficient approximation (without significant computational difficulties)
for the Probabilistic Model (referred to as an Approximate Model). The research
focuses on the analysis of traffic load-effects estimated from Weigh-in-Motion data by
calculating hypothetical load-effects that would be induced by each vehicle.
Considerations are given to single-span simply—supported and typical three—span
continuous bridges with main span lengths up to 40 m, and the load—effect results are
used as the basis for calibrating realistic probabilistic models proposed in this research.
A preliminary assessment scheme is developed to determine the quality of WIM
data, including a rational method to assist in accepting or rejecting daily data records. A
key feature is to inspect the data for consistency of the average daily single steer axle
mass distributions for selected vehicle patterns. Visual inspection of graphs of statistical
distributions is also essential for WIM data with significant temporal variations. The
site-specific traffic characteristics for each WIM site that can be derived from the
obtained WIM data are examined and presented.
A simulation study on theoretical static peak load-effects given by the obtained
WIM data was conducted in order to analyse frequency distributions of normalised peak
load-effects, normalised with respect to ‘characteristic values’. For peak load—effects
normalised with respect to the corresponding 99th percentile peak load-effects (as
characteristic values), it was found in general that the extreme normalised peak loadeffect
distributions (exceeding the load-effect thresholds) were essentially the same for
all load-effects. The peak load-effects normalised with respect to the corresponding
peak load-effects given by the T44 design load were also examined and it was found
that the T44 design load did not provide a good representation of the critical vehicles for
the traffic loads considered.
A Probabilistic Model that can be used effectively to approximate all
distributions of extreme normalised peak load-effects is developed to describe the
distributions given by general vehicles. The Probabilistic Models include an upper limit
on the maximum load-effect, and the models were validated by comparing with the
distributions of theoretical load-effects obtained from the WIM data. Furthermore, for
selected cases, they were also compared with extrapolations of extreme normalised peak
load—effects based on approximate Normal probability distributions. The resultant
distributions show that the Probabilistic Models provide an efficient basis to
approximately describe the distributions for WIM data without a large proportion of
heavily overloaded C10 (1-2-2-2) vehicles.
An example is provided for a case in which the extreme normalised peak loadeffect
distribution is not accurately described by a Normal probability distribution,
whereas sufficient accuracy is provided by a Probabilistic Model calibrated specifically
for this load-effect distribution. Extreme value distributions corresponding to sample
sizes of 1 million and 100 million vehicles were derived from the Probabilistic Models
and the Normal probability approximations for selected cases, and differences between
these extreme value distributions were inspected to study the effect of the upper limits
of the Probabilistic Models.
Finally, validation of the Approximate Models was carried out for selected cases
by comparing with the Probabilistic Models and the distributions obtained from WIM
data. An approximate threshold value for the Approximate Model is given by a
characteristic truck model capable of predicting the threshold values for all load-effects.
This truck model is based simply on the GVM information fiom the WIM data.
Satisfactory results were obtained from the characteristic truck model for describing
threshold values for all bridge types and all load-effects, using a very simple method,
and the threshold value estimation was most accurate for bridges with long main span
lengths.
The accuracy of the Approximate Model depends on the accuracy of the
characteristic truck model to estimate the threshold values. For selected cases, it has
been found that the Approximate Models provide an efficient and reasonably accurate
basis to approximate the distributions obtained from WIM data and the detailed
Probabilistic Models developed in this research.
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BALIELLO, ANDREA. "The role of road pavements in the phenomenon of Urban Heat Island." Doctoral thesis, Università degli Studi di Trieste, 2020. http://hdl.handle.net/11368/2961015.
Full textAbstract:
The thesis aims at proposing a comprehensive study concerning the role of road pavements with respect to the phenomenon of the urban heat island that are generated within the anthropized areas, i.e. all the dynamics that determine a sensible increase of the urban temperatures with respect to that recorded in the surrounding rural environments. More specifically, the core of the research concerns an extensive experimental activity aimed at evaluating different construction solutions to obtain thermal-optimized road pavements. Such solutions consist of clear or colored road pavements made with non-black surfaces and are manufactured with different techniques. Therefore, the main purpose of the whole research regards the definition of advices, indications and guidelines for the production of road pavements able to mitigate the urban heat island and prevent an excessive increase of the urban temperatures. Laboratory and outside activities were scheduled to identify the chromatic characteristics and monitor the thermal properties and responses of the selected technologies. Using a multi-scale approach (from binders to mixtures), an advanced mechanical characterization of the materials was also proposed to assess their suitability since each alternative must ensure adequate standards from functional, safety and durability points of view. A back calculation based on all the collected data permitted the evaluation of the efficacy of the proposed technologies in mitigating the urban heat. Finally, further aspects involved in the use of thermal-optimized pavements, but not directly related to thermal concerns, were also studied: mainly, such aspect regarded the infrastructure-landscape integration of clear or colored surfaces, their possible use as traffic calming measures (and the related road safety matter), their repercussions on the nightly artificial illumination or that needed within the road tunnels. Furthermore, some efforts were also spent in order to investigate their impacts with respect to the human comfort (thermal and visual ones) and the human health. Principal findings of the research stated that some technologies (clear mixtures containing synthetic transparent resins and valuable clear aggregates) were effectively able to contain the temperatures reached during the direct solar exposition (more intense in the summer). The most effective material was useful to lower the maximum reached temperature of about 18 °C with respect to that of a traditional black mixture conventionally employed as wearing courses in urban roads (assumed as reference).
24
Conradie, Johan. "Finite Element Modelling of Off-Road Tyres." Diss., University of Pretoria, 2014. http://hdl.handle.net/2263/45957.
Full textAbstract:
Most tyre models developed to date require a fair amount of data before an accurate representation of the tyre can be obtained. This study entails the development of a simplified, yet accurate, non-linear Finite Element (FE) model of an “off-road” tyre to study the behaviour of the tyre due to radial loading conditions. The study aims to develop a FE tyre model that can solve fast and be accurate enough to be used in multibody dynamic vehicle simulations. A model that is less complex than conventional detailed FE models is developed.
The work explores the use of superimposed finite elements to model the varying stiffness in the respective orthogonal directions of the sidewall and tread of the tyre. Non-linear elements defined by Neo-Hookean or Ogden models and elements with different linear orthogonal stiffnesses are superimposed onto each other to simulate the global material properties of the tread and the sidewall of the tyre investigated.
The geometry of the tyre studied was measured experimentally using laser displacement transducers and digital image correlation techniques. Material properties of segments of the tyre were obtained by performing tensile tests on samples. Since the rubber slipped against the clamps during the experiment, deformation of the segments was also measured using digital image correlation. These geometrical and material properties were used as input to develop a finite element model of an “off-road” tyre.
Measurements were conducted using laser displacement transducers, load cells mounted to actuators, etc. to obtain accurate sidewall deformation profiles and global radial load vs. displacement curves for different radial loading conditions. The data obtained from the results was used to validate the tyre model developed.
Numerous analyses are performed with different combinations of moduli of elasticity in the respective orthogonal directions of the sidewall stiffness and the tread to investigate its influence on the global behaviour of the tyre model.
The main focus of the project was to develop a tyre model from data obtained from laser and photogrammetry measurements in a laboratory that accurately represents tyre behaviour due to radial forces. A finite element model that can simulate the effect of radial forced and obstacles on a tyre was developed. The use of two subsets of elements, superimposed onto each other to simulate global material properties of the rubbers, steel wires, polyester and nylon threads, was investigated.
The combination of material properties that gave the best fit for all the load cases investigated were determined. The finite element model correlated well with the load vs. displacement graphs and sidewall displacement profiles determined experimentally.
The solving time is still fairly high and is still not quite suitable for real-time dynamic simulation. However, it solves faster than more complex tyre models where details of steel wires, etc. are included in the model.
For future studies it is recommended that different element types be investigated in the tyre model.
The study proves that equivalent material properties can be used to simulate the composite properties of the materials in tyres. Most tyres can be divided into a few regions that each has its own material structure right through the region. These regions can be characterized by simple tests and the input can be used as a first estimation of the tyre’s material properties for the model.
Accurate validation criteria should be used to validate the tyre model if time does not allow for excessive testing of the material properties of all the rubber, steel wires, polyester threads, etc. Geometric displacement data at various loading conditions can be used for validation of the tyre model.
The model developed can be used to investigate the effect of different stiffnesses and other material changes in the sidewall or tread of a tyre. Useful insight can be obtained from the finite element model developed for dynamic simulation where the force vs. global displacement data is important.Dissertation (MEng)--University of Pretoria, 2014.
tm2015
Mechanical and Aeronautical Engineering
MEng
Unrestricted
25
Appea, Alexander Kwasi. "Validation of FWD Testing Results at the Virginia Smart Road: Theoretically and by Instrument Responses." Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/26715.
Full textAbstract:
Falling weight deflectometer (FWD) is currently used by most highway agencies to determine the structural condition of the highway network. Utilizing the deflections measured by the FWD, the resilient moduli of layers in the flexible pavement is determined using backcalculation software packages. The moduli can be input into semi-empirical mechanistic equations to estimate the remaining life of the pavement system and aid in informing pavement engineers about timing of maintenance and rehabilitation needs. There have been concerns among practitioners and the research community about the adequacy of the resilient moduli determined by the backcalculation software. Some of the backcalculation models have been simplified and field verification may be needed. Field-measured stresses and strains may be used to quantify the reliability of the backcalculated moduli. The Virginia Smart Road, which has 12 different flexible pavement designs and was built and instrumented with pressure cells, strain gages, thermocouples, frost probes and moisture sensors. To validate the backcalculated moduli theoretically and through instrument response, this research was conducted with following objectives: 1) to determine the resilient moduli of the unbound granular materials on the Virginia Smart Road using small and large plates of the FWD; 2) to investigate the extent of spatial and temporal variability of the FWD deflections among pavement sections; 3) to develop a temperature correction model for the backcalculated HMA resilient moduli; 4) to define an appropriate backcalculation approach and compare the four widely used software approaches; and 5) to correlate backcalculated and laboratory measured moduli. In addition, the FWD measurements were used to establish a comparison between in-situ measured and computed stresses and strains in the pavement. The analytical approaches used are linear elastic, viscoelastic, and viscoelastic combined with nonlinearity. Results show that estimation of unbound granular materials moduli using surface deflections is more reliable when 457-mm-diameter loading plate is used. Analysis of deflections from different sensors showed evidence of spatial and temporal variability. The lowest coefficient of variation of deflections (7%) within sections occurred at low temperatures (2 to 6 °C), while the highest coefficient of variation (42%) occurred at temperatures between 35 to 40 °C. This resulted in the development of a deflection temperature correction model. The model was validated at different temperature ranges. A backcalculation procedure was defined to achieve good root mean square error using four selected software packages. This resulted in the selection of the most reliable software to perform moduli backcalculation. A correlation was established between the nonlinear models produced by backcalculation and laboratory testing of the granular 21-B material. However, for the HMA materials, difference in loading period between laboratory testing and FWD loading pulse could affect the results. The study found that when utilizing the backcalculated moduli, computed strains using viscoelastic modeling were comparable to in-situ measured values. Similarly, calculated stresses compared well with the field-measured stresses; especially at high temperatures. Mix properties, temperature of testing and loading were found to have an effect on the agreement between the measured and computed strains in the wearing surface. The study also recommended further validation of FWD measurements using embedded instruments to calibrate analytical models and further analysis of deflection data so that optimum number of testing points can be determined to limit amount of testing performed for determination of deflection variability.Ph. D.
26
Broughton, Cabot A. Carleton University Dissertation Engineering Aeronautical. "Experimental investigation of slotted wall wind tunnel test sections for low interference road vehicle testing." Ottawa, 1990.
Find full text
27
Kashaya, Asiimwe Annie. "Surface run-off behaviour of bitumen emulsions used for the construction of seals." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/80366.
Full textAbstract:
Thesis (MScEng)--Stellenbosch University, 2013.ENGLISH ABSTRACT: Factors influencing surface run-off of bitumen emulsions were studied in order to understand binders for use in the construction of surfacing seals. Run-off of the binder from the road surface causes an inconsistent film thickness leading to ravelling (Johannes, Hanz & Bahia n.d.) and bleeding at the upstream and downstream regions, respectively. There is currently no accepted specification for surface run-off viscosity. Practice mainly relies on empirical tests and experience. As the establishment of such a specification encompasses performance of the binder in various environments or field conditions, this study was undertaken to determine performance of the selected binder. Viscosity was kept constant by spraying the emulsion at a constant temperature and also holding the pavement temperature constant. In order to study the run-off behaviour of the binder, run-off tests were conducted at various gradients, texture depths and spray rates. Surfacing seals of various texture depths were constructed in the laboratory. Using a spray bar, the emulsion was sprayed at various spray rates. The sample surfaces were tilted to various gradients. Results portrayed the effects of the three factors (spray rate, gradient and texture depth) on the amount of runoff. An increase in the magnitude of the factors resulted in a variation in the runoff (increase or decrease). One notable finding was that the runoff from the 9.5 mm seal was less than that from the 13.2 mm seal. The other significant finding was that spray rate had the largest effect on runoff, followed by texture depth, and gradient.
AFRIKAANSE OPSOMMING: Sekere eienskappe wat oppervlakdreinering van bitumen emulsies op paaie beinvloed, is bestudeer om sodoende binders wat gebruik word in die konstruksie van die seëls beter te verstaan. Afloop van die binder vanaf die padoppervlak kan lei tot die vorming van ‘n laag met ongelyke dikte wat moontlike rafeling (Johannes, Hanz & Bahia nd) en bloeing vanuit die onderkant van die pad tot gevolg kan hê. Daar is tans geen aanvaarde spesifikasies wat hierdie verskynsels inperk nie. Konstruksie praktyk berus hoofsaaklik op empiriese toetse en ondervinding. Hierdie studie is dus onderneem om prestasie van die geselekteerde binder vas te stel. Viskositeit was konstant gehou deur die aangewende emulsie en padtemperatuur konstant te hou. Ten einde die afloopgedrag van die binder te bestudeer, is toetse uitgevoer op verskeie hellings, tekstuurdieptes en aanwendingskoerse. Seëls van die verskillende tekstuurdieptes is gebou in die laboratorium, en emulsies op hierdie oppervlaktes aangewend. Die toetsoppervlakte is gekantel om die vereiste helling te kry. Resultate vir die drie faktore wys die invloed op afloop. ‘n Toename in die grootte van die faktore het gelei tot 'n variasie in die afloop (toename of afname). Een noemenswaardige bevinding was dat die afloop van die seël van 9,5 mm minder was as dié van die seël van 13,2 mm. Belangrike bevindinge sluit ook in dat die spuitkoers die grootste invloed het op afloop, gevolg deur die tekstuur diepte en die gradiënt.
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Watson, Barry Craig. "The psychosocial characteristics and on-road behaviour of unlicensed drivers." Thesis, Queensland University of Technology, 2004. https://eprints.qut.edu.au/15923/1/Barry_Watson_Thesis.pdf.
Full textAbstract:
Unlicensed driving remains a serious problem for road safety, despite ongoing improvements in traffic law enforcement practices and technology. While it does not play a direct causative role in road crashes, unlicensed driving undermines the integrity of the driver licensing system and is associated with a range of high-risk behaviours. This thesis documents three studies that were undertaken to explore the scope and nature of unlicensed driving, in order to develop more effective countermeasures to the behaviour.-----
Study One utilised official road crash data from the Australian state of Queensland to compare the crash involvement patterns of unlicensed drivers with those of licensed drivers. The results confirmed that unlicensed driving is a relatively small, but significant road safety problem. Unlicensed drivers represent over 6% of the drivers involved in fatal crashes and 5% of those in serious injury crashes. Based on a quasi-induced exposure method, unlicensed drivers were found to be almost three times as likely to be involved in a crash than licensed drivers. In the event of a crash, those involving unlicensed drivers were twice as likely to result in a fatality or serious injury. Consistent with these results, the serious crashes involving unlicensed drivers were more likely to feature risky driving behaviours, such as drink driving, speeding and motorcycle use, than those involving licensed drivers.-----
Study Two involved a cross-sectional survey of 309 unlicensed driving offenders who were recruited at the Brisbane Central Magistrates Court. The survey involved a face-to-face interview that took approximately 25 minutes to complete and achieved a response rate of 62.4%. A wide range of offenders participated in the study, including: disqualified and suspended drivers; expired licence holders; drivers without a current or appropriate licence; and those who had never been licensed. The results reinforced concerns about the on-road behaviour of unlicensed drivers. Almost one quarter of all the offenders reported driving unlicensed when they thought they might have been over the alcohol limit. Similarly, 25% reported exceeding the speed limit by 10 km/h or more on most or all occasions, while 15% admitted that they didn't always wear their seat belt. In addition, the results indicated that unlicensed drivers should not be viewed as a homogeneous group. Significant differences were found between the offender types in terms of their socio-demographic characteristics (age, education level, prior criminal convictions); driving history (prior convictions for unlicensed driving and other traffic offences); whether they were aware of being unlicensed; the degree to which they limited their driving while unlicensed; and their drink driving behaviour. In particular, a more deviant sub-group of offenders was identified, that included the disqualified, not currently licensed and never licensed drivers, who reported higher levels of prior criminal offending, alcohol misuse and self-reported drink driving. The results of Study Two also highlight the shortcomings of existing police enforcement practices. Almost one-third of the sample reported that they continued to drive unlicensed after being detected by the police (up until the time of the court hearing), while many offenders reported experiences of punishment avoidance. For example, over one third of the participants reported being pulled over by the police while driving unlicensed and not having their licence checked.-----
Study Three involved the further analysis of the cross-sectional survey data to explore the factors contributing to unlicensed driving. It examined the influence of various personal, social and environmental factors on three aspects of the offenders' behaviour: the frequency of their driving while unlicensed; whether they continued to drive unlicensed after being detected; and their intentions to drive unlicensed in the future. This study was also designed to assess the capacity of a number of different theoretical perspectives to explain unlicensed driving behaviour, including deterrence theory and Akers' (1977) social learning theory. At an applied level, the results of Study Three indicated that personal and social factors exert the strongest influence over unlicensed driving behaviour. The main personal influences on unlicensed driving were: the need to drive for work purposes; exposure to punishment avoidance; personal attitudes to unlicensed driving; and anticipated punishments for the behaviour. The main social influences reflected the social learning construct of differential association, namely being exposed to significant others who both engage in unlicensed driving (behavioural dimension) and hold positive attitudes to the behaviour (normative dimension). At a theoretical level, the results of Study Three have two important implications for traffic psychology and criminology. Firstly, they provided partial support for Stafford and Warr's (1993) reconceptualisation of deterrence theory by demonstrating that the inclusion of punishment avoidance can improve the overall predictive utility of the perspective. Secondly, they suggested that social learning theory represents a more comprehensive framework for predicting illegal driving behaviours, such as unlicensed driving. This is consistent with Akers' (1977; 1990) assertion that formal deterrence processes can be subsumed within social learning theory.-----
Together, the results of the three studies have important implications for road safety. Most importantly, they question the common assumption that unlicensed drivers drive in a more cautious manner to avoid detection. While the findings indicate that many offenders reduce their overall driving exposure in order to avoid detection, this does not appear to result in safer driving. While it remains possible that unlicensed drivers tend to act more cautiously than they would otherwise, it appears that their driving behaviour is primarily designed to reduce their chances of detection. In terms of countermeasures, the research indicates that a multi-strategy approach is required to address the problem of unlicensed driving. Unlicensed drivers do not represent a homogeneous group who are likely to be influenced by the threat of punishment alone. Rather, innovative strategies are required to address the wide range of factors that appear to encourage or facilitate the behaviour. Foremost among these are punishment avoidance and the need to drive for work purposes.
29
Watson, Barry Craig. "The psychosocial characteristics and on-road behaviour of unlicensed drivers." Queensland University of Technology, 2004. http://eprints.qut.edu.au/15923/.
Full textAbstract:
Unlicensed driving remains a serious problem for road safety, despite ongoing improvements in traffic law enforcement practices and technology. While it does not play a direct causative role in road crashes, unlicensed driving undermines the integrity of the driver licensing system and is associated with a range of high-risk behaviours. This thesis documents three studies that were undertaken to explore the scope and nature of unlicensed driving, in order to develop more effective countermeasures to the behaviour.-----
Study One utilised official road crash data from the Australian state of Queensland to compare the crash involvement patterns of unlicensed drivers with those of licensed drivers. The results confirmed that unlicensed driving is a relatively small, but significant road safety problem. Unlicensed drivers represent over 6% of the drivers involved in fatal crashes and 5% of those in serious injury crashes. Based on a quasi-induced exposure method, unlicensed drivers were found to be almost three times as likely to be involved in a crash than licensed drivers. In the event of a crash, those involving unlicensed drivers were twice as likely to result in a fatality or serious injury. Consistent with these results, the serious crashes involving unlicensed drivers were more likely to feature risky driving behaviours, such as drink driving, speeding and motorcycle use, than those involving licensed drivers.-----
Study Two involved a cross-sectional survey of 309 unlicensed driving offenders who were recruited at the Brisbane Central Magistrates Court. The survey involved a face-to-face interview that took approximately 25 minutes to complete and achieved a response rate of 62.4%. A wide range of offenders participated in the study, including: disqualified and suspended drivers; expired licence holders; drivers without a current or appropriate licence; and those who had never been licensed. The results reinforced concerns about the on-road behaviour of unlicensed drivers. Almost one quarter of all the offenders reported driving unlicensed when they thought they might have been over the alcohol limit. Similarly, 25% reported exceeding the speed limit by 10 km/h or more on most or all occasions, while 15% admitted that they didn't always wear their seat belt. In addition, the results indicated that unlicensed drivers should not be viewed as a homogeneous group. Significant differences were found between the offender types in terms of their socio-demographic characteristics (age, education level, prior criminal convictions); driving history (prior convictions for unlicensed driving and other traffic offences); whether they were aware of being unlicensed; the degree to which they limited their driving while unlicensed; and their drink driving behaviour. In particular, a more deviant sub-group of offenders was identified, that included the disqualified, not currently licensed and never licensed drivers, who reported higher levels of prior criminal offending, alcohol misuse and self-reported drink driving. The results of Study Two also highlight the shortcomings of existing police enforcement practices. Almost one-third of the sample reported that they continued to drive unlicensed after being detected by the police (up until the time of the court hearing), while many offenders reported experiences of punishment avoidance. For example, over one third of the participants reported being pulled over by the police while driving unlicensed and not having their licence checked.-----
Study Three involved the further analysis of the cross-sectional survey data to explore the factors contributing to unlicensed driving. It examined the influence of various personal, social and environmental factors on three aspects of the offenders' behaviour: the frequency of their driving while unlicensed; whether they continued to drive unlicensed after being detected; and their intentions to drive unlicensed in the future. This study was also designed to assess the capacity of a number of different theoretical perspectives to explain unlicensed driving behaviour, including deterrence theory and Akers' (1977) social learning theory. At an applied level, the results of Study Three indicated that personal and social factors exert the strongest influence over unlicensed driving behaviour. The main personal influences on unlicensed driving were: the need to drive for work purposes; exposure to punishment avoidance; personal attitudes to unlicensed driving; and anticipated punishments for the behaviour. The main social influences reflected the social learning construct of differential association, namely being exposed to significant others who both engage in unlicensed driving (behavioural dimension) and hold positive attitudes to the behaviour (normative dimension). At a theoretical level, the results of Study Three have two important implications for traffic psychology and criminology. Firstly, they provided partial support for Stafford and Warr's (1993) reconceptualisation of deterrence theory by demonstrating that the inclusion of punishment avoidance can improve the overall predictive utility of the perspective. Secondly, they suggested that social learning theory represents a more comprehensive framework for predicting illegal driving behaviours, such as unlicensed driving. This is consistent with Akers' (1977; 1990) assertion that formal deterrence processes can be subsumed within social learning theory.-----
Together, the results of the three studies have important implications for road safety. Most importantly, they question the common assumption that unlicensed drivers drive in a more cautious manner to avoid detection. While the findings indicate that many offenders reduce their overall driving exposure in order to avoid detection, this does not appear to result in safer driving. While it remains possible that unlicensed drivers tend to act more cautiously than they would otherwise, it appears that their driving behaviour is primarily designed to reduce their chances of detection. In terms of countermeasures, the research indicates that a multi-strategy approach is required to address the problem of unlicensed driving. Unlicensed drivers do not represent a homogeneous group who are likely to be influenced by the threat of punishment alone. Rather, innovative strategies are required to address the wide range of factors that appear to encourage or facilitate the behaviour. Foremost among these are punishment avoidance and the need to drive for work purposes.
30
Riley, Richard James Acklom. "Developing real driving CO2 emission factors for hybrid cars through on road testing and microscale modelling." Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/17410/.
Full textAbstract:
Vehicle type approval CO2 emission figures form the basis for many countries’ national policy to reduce transport's contribution to anthropogenic climate change. However, it has become increasingly apparent that the vehicle type approval testing procedure used in Europe is not fit for purpose. There is, therefore, a need for representative real world emission factors that can be used to inform consumers, aid policy makers and provide an accurate benchmark from which type approval figures can be compared. In this work, two methods are explored to assess their feasibility to provide robust CO2 emission figures. The first is on-road vehicle activity tracking, using data collected from the vehicle controller area network. This method was chosen as it has the potential to provide large quantities of cheap, reliable data and has been demonstrated by recording over 40 parameters during testing of a third-generation Toyota Prius. This data has been used to analyse the vehicle powertrain control and provide a clear understanding of the control mechanisms that balance the engine and electrical power systems, present a comparison of the emissions of conventional and hybrid taxis giving local policy makers the underlying evidence required to introduce strong policies to reduce urban emissions from taxis and build a microscale emission model for accurate and detailed emission forecasts. The second method is microscale vehicle modelling, defined as very short time step models (1 second or less) that capture vehicle and location specific details within the model. The model requires vehicle speed and road gradient data as input and outputs second-by-second cumulative and total fuel consumed and CO2 emissions. The model has been validated against independent data (chassis dynamometer data collected by Argonne National Laboratory) and is now a powerful tool to help assess the effects of local policies (geofences, changes in the speed limit, incentives for hybrid vehicle uptake) or schemes (eco-driving) on the CO2 emissions from hybrid vehicles. This work has further developed these two methods in two ways. Firstly, by demonstrating the accuracy of controller area network data collected in vehicle activity tracking. Secondly, by demonstrating the precision of emission models built using real-world data, despite the data noise caused by real world conditions. In conclusion, these methods are well suited to providing representative real world CO2 emission factors, especially if the methods are combined. This is because vehicle activity tracking can provide the large amount of data needed for vehicle modelling and a vehicle model can provide situation specific emission factors, which, in contrary to many current emissions factors, are not only dependent on vehicle average speeds.
31
Koehler, J. F. "The development of a road profile measuring device with reference to endurance testing of motor vehicles." Master's thesis, University of Cape Town, 1990. http://hdl.handle.net/11427/8379.
Full textAbstract:
Includes bibliography.This project describes the development of a device to measure the profile of a road. The data describing the roads characteristics are used to compare the qualities of the test tracks at present used by Volkswagen SA (Pty) Ltd for endurance testing of their products, and the Synthetic Road used on their new hydraulic road simulator.
32
Taylor, Benjamin Paul. "Experimental Evaluation and Semi-Empirical Modeling of the Tractive Performance of Rigid and Flexible Wheels on Lunar Soil Simulant." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/33995.
Full textAbstract:
Understanding the effects of various wheel parameters on tractive performance is not completely understood. In order to properly quantify the individual effects of wheel parameters on the mobility of rigid and flexible wheels in soft soil, tests were performed, in cooperation with NASA Glenn Research Center (NASA-GRC), using the terramechanics rig at the Virginia Tech Advanced Vehicle Dynamics Lab (AVDL). To conduct such a study, four different wheels were evaluated under similar normal loads, slip ratios, and soil density. The first wheel represents the baseline, against which all the others were benchmarked. The remaining three wheels included the following parameter changes: 1) same diameter as the baseline but wider, 2) same width as the baseline but smaller in diameter, and 3) same width and diameter as the baseline but with a longer contact length. For each test the normal load, drawbar pull, and driving torque were measured and recorded for further analysis. To measure the effect of the changes in the wheelsâ parameters on the contact patch under different loads, a pressure pad was embedded below the surface of the Lunar simulant to measure the contact patch shape, size, and pressure distribution. Analysis of the experimental results showed that the drawbar pull was more significantly affected by the wheel diameter than by the contact width, and that same trend followed suit for the driving torque. Overall, the greater contact patch area resulted in a higher drawbar pull and torque.Master of Science
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Sharma, Balaji R. "Feasibility of use of four-post road simulators for automotive modal applications." University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1277133229.
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Hart, Susan. "Organisational barriers and facilitators to the effective operation of Random Breath Testing (RBT) in Queensland." Thesis, Queensland University of Technology, 2004. https://eprints.qut.edu.au/16451/1/Susan_Hart_Thesis.pdf.
Full textAbstract:
Random breath testing (RBT) is one of the most successful drink driving countermeasures employed by police in Australia. Its success over the years has been evidenced by reductions in drink driving behaviour, reductions in alcohol-related crashes and fatal crashes and a corresponding community-wide increase in the disapproval of drink driving. Although a great deal of research has been able to highlight the relationship between increased police enforcement and road safety benefits, little is known about the organisational factors that assist or hinder the management and operation of RBT. The purpose of this thesis is to explore the perceived barriers and facilitators to the effective operation of RBT in the Queensland Police Service (QPS). Findings will have human resource implications for the QPS and will highlight areas that are currently functioning effectively.-----
Study One involved 22 semi-structured interviews with 36 QPS managers involved in the day-to-day organisation and delivery of RBT operations. Managers were recruited with assistance from members of the QPS's State Traffic Support Branch. The interviews were approximately one hour long and involved exploration of the perceptions of managers involved in the planning and delivery of RBT operations using the concept of organisational alignment to structure the interviews. The results revealed that RBT management activity is facilitated by a range of factors, including: the belief in the importance of RBT; belief that the purpose of RBT has both a deterrent function and a detection function; the increasing use of intelligence to guide RBT strategies; the increasing use of RBT to support other crime reduction strategies; and a genuine desire to improve the current state of affairs. However, a number of apparent barriers to the effective operation of RBT were identified. These included concern about the strategy of the 1.1 testing strategy (i.e. conducting the equivalent of one test per licensed driver per annum), a misunderstanding of the role of general and specific deterrence and a lack of feedback in relation to the success of RBT.-----
The second study involved a questionnaire that was distributed to a random sample of 950 operational police stratified across the regions who are responsible for undertaking RBT on a regular basis. There were 421 questionnaires returned representing a response rate of 44%. Questionnaires were also based on the concepts and constructs of organisational alignment and explored perceptions, beliefs and self- reported behaviour of officers. The results revealed that facilitating factors included a belief in QPS ownership of the RBT program, the agreement that the RBT vision includes road safety goals and apprehension goals, and overall motivation, support and belief in their capability to carry out RBT duties. Barriers included perceived strain related to the 1:1 testing strategy, the lack of feedback in relation to the success of RBT, misunderstanding about the role of deterrence and lack of rewards for participating in RBT duties.-----
The results of both studies have implications for the planning and operation of RBT in the QPS. While the findings revealed that there were many aspects of the RBT program that were currently aligned with best practice guidelines, there are areas of misalignment. In particular, the main areas of misalignment included concern about the strain caused by the current 1:1 testing strategy, a lack of feedback about the success of RBT and a lack of education of the nature and role of deterrence in road safety and RBT operations in particular.
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Hart, Susan. "Organisational barriers and facilitators to the effective operation of Random Breath Testing (RBT) in Queensland." Queensland University of Technology, 2004. http://eprints.qut.edu.au/16451/.
Full textAbstract:
Random breath testing (RBT) is one of the most successful drink driving countermeasures employed by police in Australia. Its success over the years has been evidenced by reductions in drink driving behaviour, reductions in alcohol-related crashes and fatal crashes and a corresponding community-wide increase in the disapproval of drink driving. Although a great deal of research has been able to highlight the relationship between increased police enforcement and road safety benefits, little is known about the organisational factors that assist or hinder the management and operation of RBT. The purpose of this thesis is to explore the perceived barriers and facilitators to the effective operation of RBT in the Queensland Police Service (QPS). Findings will have human resource implications for the QPS and will highlight areas that are currently functioning effectively.-----
Study One involved 22 semi-structured interviews with 36 QPS managers involved in the day-to-day organisation and delivery of RBT operations. Managers were recruited with assistance from members of the QPS's State Traffic Support Branch. The interviews were approximately one hour long and involved exploration of the perceptions of managers involved in the planning and delivery of RBT operations using the concept of organisational alignment to structure the interviews. The results revealed that RBT management activity is facilitated by a range of factors, including: the belief in the importance of RBT; belief that the purpose of RBT has both a deterrent function and a detection function; the increasing use of intelligence to guide RBT strategies; the increasing use of RBT to support other crime reduction strategies; and a genuine desire to improve the current state of affairs. However, a number of apparent barriers to the effective operation of RBT were identified. These included concern about the strategy of the 1.1 testing strategy (i.e. conducting the equivalent of one test per licensed driver per annum), a misunderstanding of the role of general and specific deterrence and a lack of feedback in relation to the success of RBT.-----
The second study involved a questionnaire that was distributed to a random sample of 950 operational police stratified across the regions who are responsible for undertaking RBT on a regular basis. There were 421 questionnaires returned representing a response rate of 44%. Questionnaires were also based on the concepts and constructs of organisational alignment and explored perceptions, beliefs and self- reported behaviour of officers. The results revealed that facilitating factors included a belief in QPS ownership of the RBT program, the agreement that the RBT vision includes road safety goals and apprehension goals, and overall motivation, support and belief in their capability to carry out RBT duties. Barriers included perceived strain related to the 1:1 testing strategy, the lack of feedback in relation to the success of RBT, misunderstanding about the role of deterrence and lack of rewards for participating in RBT duties.-----
The results of both studies have implications for the planning and operation of RBT in the QPS. While the findings revealed that there were many aspects of the RBT program that were currently aligned with best practice guidelines, there are areas of misalignment. In particular, the main areas of misalignment included concern about the strain caused by the current 1:1 testing strategy, a lack of feedback about the success of RBT and a lack of education of the nature and role of deterrence in road safety and RBT operations in particular.
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Horký, Martin. "Měření aerodynamických charakteristik vozidla na základě jízdních testů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231526.
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Weller, Gert. "The Psychology of Driving on Rural Roads: Development and Testing of a Model." Springer, 2009. https://tud.qucosa.de/id/qucosa%3A34464.
Full textAbstract:
Rural roads constitute the most dangerous road category with regard to the number of fatal accidents. In order to increase traffic safety on rural roads it is necessary to take into account not only their inherent properties but also their effect on behaviour. Gert Weller develops a psychological model for driving on rural roads which is validated in three empirical steps: laboratory, simulator and driving experiments. His results provide insight into the possibilities of how driving behaviour on rural roads can be influenced and give practical guidance for the enhancement of rural road safety.
The book is written for psychologists in the fields of traffic psychology and human factors research, traffic engineers, road planners as well as for political decision makers in traffic planning departments.:1. Driving on Rural Roads: The Current Situation
2. Applying Existing Models to Driving on Rural Roads
2.1. A Framework
2.2. Individual Differences: Traits and Demographic Variables
2.3. Driving as a Self-Paced Task: Motivational Models
2.4. Perception and Information-Processing
3. A Psychological Model for Driving on Rural Roads
4. Empirical Validation
4.1. Overview and General Course of Events
4.2. The Laboratory Study: The Role of Perceived Road Characteristics
4.3. The Simulator Study: The Role of Cues and Affordances
4.4. On-the-Road Driving Tests: Behaviour and Accidents
5. Empirical Validation: Summary and Conclusions
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Mendes, Tatiana Sussel Gonçalves. "Extração semi-automática de rodovias em imagens digitais usando técnicas de correlação e o princípio de teste ativo /." Presidente Prudente : [s.n.], 2005. http://hdl.handle.net/11449/88530.
Full textAbstract:
Orientador: Aluir Porfírio Dal PozResumo: É esperado que o operador humano permaneça, por um longo tempo, como parte integrante do sistema de extração de feições. Portanto, as pesquisas que caminham para o desenvolvimento de novos métodos semi-automáticos são ainda de grande importância. Nesta linha, esta pesquisa propõe um método semi-automático para a extração de rodovias em imagens digitais. A metodologia é uma combinação entre técnicas de correlação e estratégia de teste ativo. Os resultados experimentais obtidos da aplicação do método em imagens reais mostram que o método funciona corretamente, demonstrando que pode ser usado em esquemas de captura de dados.
Abstract: The human operator is still expected to remain as part of the feature extraction system for a relative long time. Therefore, researches for the development of new semi-automatic methods is still of great importance. Following this line, this research proposes a semi-automatic method for road extraction from digital images. It is based on a combination between correlation techniques and an active testing strategy. In order to initialize the extraction process, the operator needs to supply two close seed points plus another one at the end of road segment selected to be extracted. Experimental results obtained from the application of the method to real image data show that the method works properly, demonstrating that the developed method can be used in data capturing schemes.
Mestre
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Sumon, Sarwan Kumar. "Innovative and effective transport solutions for masonry arch bridges, safety barriers and road humps through testing and numerical simulation." Thesis, University of Ulster, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.446253.
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COCONEA, LAURA DANIELA. "Analysis, simulation and testing of ITS applications based on wireless communication technologies." Doctoral thesis, Politecnico di Torino, 2015. http://hdl.handle.net/11583/2598394.
Full textAbstract:
Intelligent Transportation Systems (ITS) aim to improve road transport safety and efficiency, to manage road networks in the interest of the society and to provide real time responses to events. In order to reach these goals, real time feedback to the drivers is expected through the integration of telecommunications, sensing and information technologies with transport engineering. Wireless communication technologies, that have been used in industrial applications for more than 30 years, play a crucial role in ITS, as based on the concept of multiple devices (on both vehicle and infrastructure side) interconnected in different ways.
Connectivity, in tandem with sensing technologies, is fuelling the innovations that will inevitably lead to the next big opportunity for road transport: autonomous vehicles.
Therefore, this study has investigated - through analysis, simulation and field testing – on applications based on wireless communication technologies meant to support both Data acquisition and Data diffusion as fundamental aspects/ phases in ITS, where data is widely individuated as being the key element.
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Gover, Rory Benjamin. "Experimental impact and finite element analysis of a composite, portable road safety barrier." Thesis, Queensland University of Technology, 2013. https://eprints.qut.edu.au/62339/7/Rory_Gover_Thesis.pdf.
Full textAbstract:
This thesis provides an experimental and computational platform for investigating the performance and behaviour of water filled, plastic portable road safety barriers in an isolated impact scenario. A schedule of experimental impact tests were conducted assessing the impact response of an existing design of road safety barrier utilising a novel horizontal impact testing system. A coupled finite element and smooth particle hydrodynamic model of the barrier system was developed and validated against the results of the experimental tests. The validated model was subsequently used to assess the effect of certain composite materials on the impact performance of the water filled, portable road safety barrier system.
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Shea, Edward. "Calibration of Snowmaking Equipment for Efficient Use on Virginia's Smart Road." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/44622.
Full textAbstract:
Virginia's Smart Road, to be completed by early 2000, is a test bed for numerous research activities including snow and ice control, remote sensor testing, snow removal management, safety and human factors, and vehicle dynamics. An all-weather testing system will feature 75 automated snowmaking towers. In order to provide timely and repeatable weather scenarios, equipment operators will need to understand fully the limitations and capabilities of the snowmaking system.
The research presented herein addresses the hydraulic and hydrologic variables and design methodology to implement efficient snowmaking at a transportation research facility. Design variables include nozzle configuration, water pressure and flowrate, compressed air pressure and flowrate, tower orientation, snow inducer concentration, water and compressed air temperature, and ambient weather conditions. Testing and data collection was performed at the Snow Economics, Inc. research and development site at Seven Springs Mountain Resort in Champion, PA. The results of this work will be used to guide the operators of the Smart Road on the most efficient use of the snowmaking equipment.Master of Science
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Lombard, Le Riche. "Influence of surface seal variables on bitumen bond strength properties." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/95882.
Full textAbstract:
Thesis (MScEng)--Stellenbosch University, 2014.ENGLISH ABSTRACT: Surface seals are widely used in South Africa. There are a number of reasons which include affordability, versatility and durability. There are, however, in some cases problems with stone loss that can lead to a shortened lifespan of the pavement. The loss of aggregate chippings in surface seals poses a major problem in the seal pavement industry. This study aims to identify the influencing factors that lead to these adhesive failures as well as to find optimum combinations of binders and aggregates at various conditions. Various binders commonly used in South African surface seal construction will be tested using the Bitumen Bond Strength (BBS) test method. The binders used in the study include 80/100 penetration grade bitumen, elastomer modified bitumen, bitumen rubber, elastomer modified emulsion and cationic rapid setting emulsion. Aggregates used in the study include dolerite, granite and quartzite. The test samples were cured and tested at two temperatures, 15 °C and 35 °C. The samples were also cured for 2, 6 and 24 hours respectively. The study tackles a wide range of variables in order to obtain a good understanding of adhesion properties of surface seals used in South Africa. Tests were repeated at least once to ensure repeatability and in some cases up to four repeats were performed. The loading rate at which the tests were performed had a significant influence on the BBS results. This rate varied which complicated the process of comparing the results. It was therefore decided to unify the loading rates. The BBS results exposed the difference between hot applied binders and emulsions. The former having significant stronger adhesion properties. It was also confirmed by the results that temperature plays a key role in the BBS results due to the visco-elastic properties of bitumen. These influences will be discussed along with others such as aggregate types and curing times. The type of failure is also discussed. Failure can either be adhesive or cohesive, the former being a failure between the aggregate and the binder while the later refers to a failure in the binder itself. The results of other students will also be discussed and compared to the results of this study. These include results of predecessors that tested emulsions as well as results from tests done on fractured aggregate surfaces and precoated aggregates. This study showed very similar results as these from other students, except for tests done with emulsions. It was discovered that the method of curing of the emulsions must be adapted to ensure proper curing of the emulsions. It was found that aggregates did not influence the BBS properties to the same extent as temperature and binder application type. The BBS results of hot applied binders also did not significantly increase as the curing time increased, but the results of emulsions showed some increase. However, the emulsions needed more time to cure properly.
AFRIKAANSE OPSOMMING: Oppervlak seëls word algemeen gebruik in Suid-Afrika. Daar is verskeie redes hiervoor waaronder bekostigbaarheid,veelsydigheid en duursaamheid. Daar is egter in sommige gevalle probleme met klipverlies wat kan lei tot n verkorte leeftyd. Hierdie klipverlies ontstaan as gevolg van verskeie redes of kombinasies daarvan. Die studie beoog om hierdie faktore wat die adhesie eienskappe beïnvloed te identifiseer sowel as om optimum kobinasies van bindmiddels en klipsoorte te bewerkstellig by verkeie kondisies. ‘n Verskeidenheid van bindmiddels wat algemeen in Suid-Afrika gebruik word, word in die studie getoets met die Bitumen Bond Sterkte (BBS) toets metode. Die bindmiddels wat in die studie gebruik word sluit 80/100 penetrasie graad bitumen, elastomeer gemodifiseerde bitumen, bitumen rubber, elastomeer gemodifiseerde emulsie en kationiese snel settende emulsie. Die klipsoorte wat vir die studie gebruikword is doleriet, graniet en kwartsiet. Hierdie gesteentes word algemeen in die praktyk gebruik. Die toets monsters word ook by twee temperature gekuur en getoets. Hierdie temperature is 15 °C en 35 °C. Die toets monsters word ook onderskeidelik vir 2, 6 en 24 uur gekuur. Die studie ondersoek 'n wye verskeidenheid van veranderlikes om sodoende 'n goeie begrip van adhesie eienskappe van die oppervlak seëls wat in Suid-Afrika gebruik word te verkry. Elke toets was ten minste een maal herhaal om herhaalbaarheid te verseker. Sommige toetse was tot 4 keer herhaal. Die belasting tempo van die toetse het ‘n beduidende uitwerking op die BBS resultate as gevolg van die visko-elastiese eienskappe van bitumen. Hierdie tempo het gewissel en dit moeilik gemaak om die resultate te vergelyk. Daarom was daar besluit om die tempo van die toetse te verander na ‘n gelykvormige tempo. Daar was ‘n duidelike verskil in BBS resultate van die warm toegepaste bindmiddels en die emulsies. Die warm bindmiddels het baie hoër BBS resultate gelwer. Dit was ook bevestig in die resultate dat temperatuur ‘n beduidende rol speel in die BBS. Hierdie invloede sal bespreek word tesame met ander, soos klipsoorte en kuring tye. Die tipe versaking word ook bespreek. Versaking kan plaasvind as gevolg van adhesie of cohesie, waar adhesie versaking 'n versaking is tussen die klip en die bindmiddel terwyl cohesie versaking verwys na 'n versaking in die bindmiddel self. Die uitslae van die ander studente sal ook bespreek word en vergelyking word met die resultate van hierdie studie. Dit sluit die resultate van voorgangers in wat emulsies getoets het sowel as die resultate van toetse wat gedoen is op gebreekte klipoppervlaktes en bitumen behandelde klippe. Hierdie studie het baie soortgelyke resultate getoon as dié van ander studente, behalwe vir die toetse wat gedoen was met emulsies. Daar is vasgestel dat die metode van kuring van die emulsies moet aangepas word om behoorlike kuring van die emulsies te verseker. Daar is ook gevind dat klipsoorte nie die BBS eienskappe in dieselfde mate as temperatuur en bindmiddel toepassingstipe beïnvloed het nie. Die BBS resultate van warm aangewende bindmiddels het ook nie aansienlik verhoog soos die kuringstyd toegeneem het nie, maar die resultate van emulsies het wel 'n toename getoon. Die emulsies het wel meer tyd nodig gehad om behoorlik te kuur.
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Kozuka, Ryohei. "Studded tire wear - comparison between British Pendulum and Pin on disc testing." Thesis, KTH, Maskinkonstruktion (Avd.), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-209485.
Full textAbstract:
Studded tires are widely used during the winter season in the Nordic countries due to their performance qualities in extreme cold temperatures, however they cause wear on the road surface. This is not only an economic problem but also a health problem due to amount of airborne wear particles that are generated. Therefore, a test method under controlled laboratory conditions for tire and road wear is needed. In this thesis,studded tire wear on concrete road samples are studied using two test equipments; a Pin on disc and a British pendulum rig test. Three different types of concrete road materials and two different types of tire stud geometries were used in the study. The road sample wear ranks the same in both test equipment’s following the rebound hardness of the concrete material. For the two studded tires samples differences in the amount of wear could be noticed. One possible explanation here is the wear dependence on the velocity due to the difference in simulated vehicle speed for the two tests equipment’s.Dubbdäck används i stor utsträckning under vintersäsongen i Norden på grund av deras prestandaegenskaper i kalla temperaturer. Ett problem med dubbdäck är att de orsakar slitage på vägytan. Detta är inte bara ett ekonomiskt problem utan också ett hälsoproblem då en del av slitaget är partiklar som är luftburna och inandningsbara. Därför finns det ett behov av testmetoder för däck och vägslitage i kontrollerad laboratoriemiljö. I denna studie utvärderas dubbdäcksnötning i två testutrustningar; den brittiska vägpendeln och en pinne-på-skiva maskin. Prov utfördes med tre olika vägvarianter av betong och två olika dubbgeometrier. Storleken på nötningen rankades den samma för de olika vägbeläggningarna i de två olika provutrustningarna. Dock så inverkade dubbgeometrin på resultatet och olika nivåer på vägslitage kunde noteras för de två dubbvarianterna i beroende på val av provutrustning. En möjlig förklaring kan vara ett hastighetsberoende av nötningen då de två olika provutrustningarna simulerar olika fordonshastigheter.
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He, Rui. "Systematic Tire Testing and Model Parameterization for Tire Traction on Soft Soil." Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/104386.
Full textAbstract:
Tire performance over soft soil influences the performance of off-road vehicles on soft soil, as the tire is the only force transmitting element between the off-road vehicles and soil during the vehicle operation. One aspect of the tire performance over soft soil is the tire tractive performance on soft soil, and it attracts the attention of vehicle and geotechnical engineers. The vehicle engineer is interested in the tire tractive performance on soft soil because it is related to vehicle mobility and energy efficiency; the geotechnical engineer is concerned about the soil compaction, brought about by the tire traffic, which accompanies the tire tractive performance on soft soil. In order to improve the vehicle mobility and energy efficiency over soft soil and mitigate the soil compaction, it's essential to develop an in-depth understanding of tire tractive performance on soft soil.
This study has enhanced the understanding of tire tractive performance on soft soil and promoted the development of terramechanics and tire model parameterization method through experimental tests. The experimental tests consisted of static tire deflection tests, static tire-soil tests, soil properties tests, and dynamic tire-soil tests. The series of tests (test program) presented herein produced parameterization and validation data that can be used in tire off-road traction dynamics modeling and terramechanics modeling.
The 225/60R16 97S Uniroyal (Michelin) Standard Reference Test Tire (SRTT) and loamy sand were chosen to be studied in the test program. The tests included the quantification or/and measurement of soil properties of the test soil, pre-traffic soil condition, the pressure distribution in the tire contact patch, tire off-road tractive performance, and post-traffic soil compaction. The influence of operational parameters, e.g., tire inflation pressure, tire normal load, tire slip ratio, initial soil compaction, or the number of passes, on the measurement data of tire performance parameters or soil response parameters was also analyzed. New methods of the rolling radius estimation for a tire on soft soil and of the 3-D rut reconstruction were developed. A multi-pass effect phenomenon, different from any previously observed phenomenon in the available existing literature, was discovered.
The test data was fed into optimization programs for the parameterization of the Bekker's model, a modified Bekker's model, the Magic Formula tire model, and a bulk density estimation model. The modified Bekker's model accounts for the slip sinkage effect which the original Bekker's pressure-sinkage model doesn't. The Magic Formula tire model was adapted to account for the combined influence of tire inflation pressure and initial soil compaction on the tire tractive performance and validated by the test data. The parameterization methods presented herein are new effective terramechanics model parameterization methods, can capture tire-soil interaction which the conventional parameterization methods such as the plate-sinkage test and shear test (not using a tire as the shear tool) cannot sufficiently, and hence can be used to develop tire off-road dynamics models that are heavily based on terramechanics models.
This study has been partially supported by the U.S. Army Engineer Research and Development Center (ERDC) and by the Terramechanics, Multibody, and Vehicle (TMVS) Laboratory at Virginia Tech.Doctor of Philosophy
Big differences exist between a tire moving in on-road conditions, such as asphalt lanes, and a tire moving in off-road conditions, such as soft soil. For example, for passenger cars commonly driven on asphalt lanes, normally, the tire inflation pressure is suggested to be between 30 and 35 psi; very low inflation pressure is also not suggested. By contrast, for off-road vehicles operated on soft soil, low inflation pressure is recommended for their tires; the inflation pressure of a tractor tire can be as low as 12 psi, for the sake of low post-traffic soil compaction and better tire traction. Besides, unlike the research on tire on-road dynamics, the research on off-road dynamics is still immature, while the physics behind the off-road dynamics could be more complex than the on-road dynamics. In this dissertation, experimental tests were completed to study the factors influencing tire tractive performance and soil behavior, and model parameterization methods were developed for a better prediction of tire off-road dynamics models. Tire or vehicle manufacturers can use the research results or methods presented in this dissertation to offer suggestions for the tire or vehicle operation on soft soil in order to maximize the tractive performance and minimize the post-traffic soil compaction.
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Palm, Alexander, and Benjamin Gafvelin. "Ethical Hacking of Android Auto in the Context of Road Safety." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-299647.
Full textAbstract:
With a more than ever increasing demand to interconnect smartphones with infotainment systems, Android Auto has risen in popularity with its services used in modern vehicles worldwide. However, as users progressively connect their smartphones to in-vehicle infotainment systems, the opportunity for malicious actors to endanger and access private data of Android Auto users advances as well. The goal with this thesis is to determine how secure Android Auto is for road use. The main research question is to figure out if Android Auto is susceptible to attacks that exploit certain vulnerabilities in the Android operating system. The research question was answered by creating several proof-of-concept attacks on Android Auto using an emulated infotainment system with mobile devices. An investigation was also conducted regarding the application’s communication channel between the mobile device and infotainment display. Results of this thesis demonstrate that several attacks are substantially severe to endanger drivers on the road. There is a great risk of successful exploits when running Android Auto locally on the phone without a connection to the infotainment system, and a lesser risk when connected to the infotainment system. Intercepting communication in the USB channel revealed an encryption algorithm whose version has published exploits and can be cracked to potentially exploit Android Auto.I takt med en evigt ökande efterfrågan på att sammankoppla smarttelefoner med infotainmentsystem, har allt fler börjat använda Android Auto i sina fordon världen över. En bieffekt av att allt fler sammankopplar sina mobiler till infotainmentsystem, är att det leder till fler möjligheter för illvilliga parter att stjäla privat data och sätta Android Autoanvändares liv i fara. Målet med denna avhandling är att fastställa hur säkert Android Auto är i avseende till vägsäkerhet. Den huvudsakliga forskningsfrågan är att lista ut om Android Auto kan attackeras av attacker som utnyttjar sårbarheter i Android operativsystemet. Forskningsfrågan besvarades genom att skapa flertal konceptattacker mot Android Auto användandes av ett emulerat infotainmentsystem och mobiltelefoner. En utredning utfördes även gällande applikationens kommunikationskanal mellan telefonen och infotainmentskärmen. Resultatet från denna avhandling demonstrerade att många attacker är tillräckligt allvarliga för att äventyra trafikanternas säkerhet. Det finns en avsevärd risk för framgångsrika attacker när Android Auto körs lokalt på telefonen utan en USB koppling till infotainmentsystemet, och en liten risk när telefonen är kopplad till infotainmentsystemet. Avlyssning och uppfångning av kommunikationen i USB kanalen visade att en krypteringsalgoritm vars version har existerande sårbarheter kan avkrypteras och utnyttjas för att potentiellt attackera Android Auto.
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Davis, Lloyd Eric. "Heavy vehicle suspensions : testing and analysis." Thesis, Queensland University of Technology, 2010. https://eprints.qut.edu.au/34499/1/Lloyd_Davis_Thesis.pdf.
Full textAbstract:
Transport regulators consider that, with respect to pavement damage, heavy vehicles (HVs) are the riskiest vehicles on the road network. That HV suspension design contributes to road and bridge damage has been recognised for some decades. This thesis deals with some aspects of HV suspension characteristics, particularly (but not exclusively) air suspensions. This is in the areas of developing low-cost in-service heavy vehicle (HV) suspension testing, the effects of larger-than-industry-standard longitudinal air lines and the characteristics of on-board mass (OBM) systems for HVs. All these areas, whilst seemingly disparate, seek to inform the management of HVs, reduce of their impact on the network asset and/or provide a measurement mechanism for worn HV suspensions. A number of project management groups at the State and National level in Australia have been, and will be, presented with the results of the project that resulted in this thesis. This should serve to inform their activities applicable to this research. A number of HVs were tested for various characteristics. These tests were used to form a number of conclusions about HV suspension behaviours. Wheel forces from road test data were analysed. A “novel roughness” measure was developed and applied to the road test data to determine dynamic load sharing, amongst other research outcomes. Further, it was proposed that this approach could inform future development of pavement models incorporating roughness and peak wheel forces. Left/right variations in wheel forces and wheel force variations for different speeds were also presented. This led on to some conclusions regarding suspension and wheel force frequencies, their transmission to the pavement and repetitive wheel loads in the spatial domain. An improved method of determining dynamic load sharing was developed and presented. It used the correlation coefficient between two elements of a HV to determine dynamic load sharing. This was validated against a mature dynamic loadsharing metric, the dynamic load sharing coefficient (de Pont, 1997). This was the first time that the technique of measuring correlation between elements on a HV has been used for a test case vs. a control case for two different sized air lines. That dynamic load sharing was improved at the air springs was shown for the test case of the large longitudinal air lines. The statistically significant improvement in dynamic load sharing at the air springs from larger longitudinal air lines varied from approximately 30 percent to 80 percent. Dynamic load sharing at the wheels was improved only for low air line flow events for the test case of larger longitudinal air lines. Statistically significant improvements to some suspension metrics across the range of test speeds and “novel roughness” values were evident from the use of larger longitudinal air lines, but these were not uniform. Of note were improvements to suspension metrics involving peak dynamic forces ranging from below the error margin to approximately 24 percent. Abstract models of HV suspensions were developed from the results of some of the tests. Those models were used to propose further development of, and future directions of research into, further gains in HV dynamic load sharing. This was from alterations to currently available damping characteristics combined with implementation of large longitudinal air lines. In-service testing of HV suspensions was found to be possible within a documented range from below the error margin to an error of approximately 16 percent. These results were in comparison with either the manufacturer’s certified data or test results replicating the Australian standard for “road-friendly” HV suspensions, Vehicle Standards Bulletin 11. OBM accuracy testing and development of tamper evidence from OBM data were detailed for over 2000 individual data points across twelve test and control OBM systems from eight suppliers installed on eleven HVs. The results indicated that 95 percent of contemporary OBM systems available in Australia are accurate to +/- 500 kg. The total variation in OBM linearity, after three outliers in the data were removed, was 0.5 percent. A tamper indicator and other OBM metrics that could be used by jurisdictions to determine tamper events were developed and documented. That OBM systems could be used as one vector for in-service testing of HV suspensions was one of a number of synergies between the seemingly disparate streams of this project.
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Roughan, Craig. "Adaptive brake lights : an investigation into their relative benefits in regards to road safety." Thesis, Queensland University of Technology, 2007. https://eprints.qut.edu.au/16335/1/Craig_Roughan_Thesis.pdf.
Full textAbstract:
The implementation of In-Vehicle Intelligent Transport Systems (ITS) is becoming a common occurrence in modern vehicles. Automobile manufacturers are releasing vehicles with many forms of sophisticated technologies that remove much of the responsibility of controlling an automobile from the driver. These In-Vehicle Intelligent Transport Systems have stemmed from a genuine need in regards to road safety, however there are advantages and disadvantages associated with ITS. Each different form of technology has its own inherent compromises in relation to road safety, driver behaviour and driver comfort.
This thesis outlines the benefits and detrimental effects associated with current In-Vehicle Intelligent Transport Systems and details the development and user interface testing of an adaptive brake light. The adaptive brakelight concept aims to provide drivers with the advantages of an In-Vehicle ITS whilst removing the disadvantages. The technology will help drivers judge the braking pattern of the car in front, thus allowing them to react appropriately and potentially reducing the occurrence of rear-end crashes.
The adaptive brake light concept was tested in comparison to a standard brake light and BMW inspired brake light in a series of user interface tests. The adaptive brake light was shown overall to be an improved method of displaying the varying levels of deceleration of a lead vehicle. Whilst different age and gender groups responded differently to the adaptive brake light, it was shown to be of benefit to the majority and the most at risk groups responded positively to the adaptive brake light.
This research shows that an adaptive brake light can provide a benefit in regards to road safety when compared to a standard brake light interface. It is hoped that further development of variable brake lights will result from this research and possibly lead to the implementation of the technology to automobiles and other forms of transport.
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Roughan, Craig. "Adaptive brake lights : an investigation into their relative benefits in regards to road safety." Queensland University of Technology, 2007. http://eprints.qut.edu.au/16335/.
Full textAbstract:
The implementation of In-Vehicle Intelligent Transport Systems (ITS) is becoming a common occurrence in modern vehicles. Automobile manufacturers are releasing vehicles with many forms of sophisticated technologies that remove much of the responsibility of controlling an automobile from the driver. These In-Vehicle Intelligent Transport Systems have stemmed from a genuine need in regards to road safety, however there are advantages and disadvantages associated with ITS. Each different form of technology has its own inherent compromises in relation to road safety, driver behaviour and driver comfort. This thesis outlines the benefits and detrimental effects associated with current In-Vehicle Intelligent Transport Systems and details the development and user interface testing of an adaptive brake light. The adaptive brakelight concept aims to provide drivers with the advantages of an In-Vehicle ITS whilst removing the disadvantages. The technology will help drivers judge the braking pattern of the car in front, thus allowing them to react appropriately and potentially reducing the occurrence of rear-end crashes. The adaptive brake light concept was tested in comparison to a standard brake light and BMW inspired brake light in a series of user interface tests. The adaptive brake light was shown overall to be an improved method of displaying the varying levels of deceleration of a lead vehicle. Whilst different age and gender groups responded differently to the adaptive brake light, it was shown to be of benefit to the majority and the most at risk groups responded positively to the adaptive brake light. This research shows that an adaptive brake light can provide a benefit in regards to road safety when compared to a standard brake light interface. It is hoped that further development of variable brake lights will result from this research and possibly lead to the implementation of the technology to automobiles and other forms of transport.
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Nygren, Richard Edwin 1964. "Predictive Validity of the Retail Employment Inventory for the Selection of Over-the-Road Truck Drivers." Thesis, North Texas State University, 1988. https://digital.library.unt.edu/ark:/67531/metadc500969/.
Full textAbstract:
An independent pilot study suggested that the Retail Employment Inventory (REI) might be predictive of subjectively and objectively measured Over the Road (OTR) truck driver performance. The present validation study consisted of three parts. First, an examination of the relationship between REI scores and 11 objective, performance criteria revealed weak and non-significant correlations. Second, a comparison of subjective ratings and REI scores failed to replicate the findings of the pilot study. And third, to confirm that the task components of the OTR job were correctly identified in the pilot study, a second job analysis was performed. Possible reasons for the failure of the REI to predict OTR performance and directions for future research are discussed.