The evolution of vehicle safety systems, from the earliest brakes to today's accident avoidance systems, has led vehicles to have very high passenger safety. Driving on ice, though, still happens to be one of the driving conditions of low safety. A multitude of factors were identified by various studies to contribute to the complex frictional mechanism at the tire-ice interface. The tire is only force transmitting element of the vehicle, to the surface. Thus it is very essential to have in depth understanding of the contact phenomena at the tire-ice interface, to improve vehicle safety on icy roads. This study has led to understanding of the contact phenomena at the tire-ice contact through experimental studies and a semi-empirical based tire-ice contact model. Experimental studies included both indoor testing and outdoor testing, indoor testing was conducted using the Terramechanics Rig at the Advanced Vehicle Dynamics in Virginia Tech and field tests were conducted at the Keweenaw Research Center in Michigan Tech. The simulation results of the tire-ice model were validated against the findings of the indoor test program. The P225/60R16 97S Standard Reference Test Tire was the candidate tire for this study. The effects of operational parameters, were studied when in driving traction by comparison of the friction - slip ratio curves. The two tests procedures were performed to understand how each test method influences the test results. A comparison of the laboratory and field test method are also presented, with reasons for the differences in the measured values presented. The experimental study also led to development of a modular structured tire-ice model (TIM). The model computes the temperature rise in the contact patch based on the pressure distribution in the contact patch, thermal properties of the tread compound and of the ice surface. The contact patch is then classified into wet and dry regions based on the ice surface temperature and temperature rise simulations. The principle of thermal balance is then applied to compute the friction level in the contact patch. The tire-ice contact model is validated for two parameters: temperature rise and friction levels. Temperature rise from simulations are validated against temperature measurements at the leading and trailing edge of the contact patch. Friction levels at different conditions of load, inflation pressure, and ice temperatures have been simulated using the tire-ice contact model and compared to the experimental findings. / Ph. D.

Thesis (M.S.M.)--University of Toledo, 2005. / Typescript. "A thesis [submitted] as partial fulfillment of the requirements of the Master of Science degree in Mechanical Engineering." Bibliography: leaves 94-95.

Thesis (M. Sc.)--University of Hong Kong, 2005.

Thesis (M. Sc.)--University of Hong Kong, 1996. / Includes bibliographical references (leaf [66-68]).

Pressures from environmental agencies contribute to the challenges associated with the disposal of waste tyres, particularly in South Africa. Recycling of waste tyres in South Africa is in its infancy resulting in the historically undocumented and uncontrolled existence of waste tyre stockpiles across the country. The remote and distant locations of such stockpiles typically complicate the logistics associated with the collection, transport and storage of waste tyres prior to entering the recycling process. In order to optimize the logistics associated with the collection of waste tyres from stockpiles, useful information about such stockpiles would include estimates of the types of tyres as well as the quantity of specific tyre types found in particular stockpiles. This research proposes the use of computer vision for categorizing individual tyres and estimating the number of visible tyres in tyre stockpile images to support the logistics in tyre recycling efforts. The study begins with a broad review of image processing and computer vision algorithms for categorization and counting objects in images. The bag of visual words (BoVW) model for categorization is tested on two small data sets of tread tyre images using a random sub-sampling holdout method. The categorization results are evaluated using performance metrics for multiclass classifiers, namely the average accuracy, precision, and recall. The results indicated that corner-based local feature detectors combined with speeded up robust features (SURF) descriptors in a BoVW model provide moderately accurate categorization of tyres based on tread images. Two feature extraction methods for extracting features for use in training neural networks (NNs) for tyre count estimations in tyre stockpiles are proposed. The two feature extraction methods are used to describe images in terms of feature vectors that can be used as input for NNs. The first feature extraction method uses the BoVW model with histograms of oriented gradients (HOG) features collected from overlapping sub-images to create a visual vocabulary and describe the images in terms of their visual word occurrence histogram. The second feature extraction method uses the image gradient magnitude, gradient orientation, and edge orientations of edges detected using the Canny edge detector. A concatenated histogram is constructed from individual histograms of gradient orientations and gradient magnitude. The histograms are then used to train NNs using backpropogation to approximate functions from the feature vectors describing the images to scalar count estimations. The accuracy of visible object count predictions are evaluated using NN evaluation techniques to determine the accuracy of predictions and the generalization ability of the fit model. The count estimation experiments using the two feature extraction methods for input to NNs showed that fairly accurate count estimations can be obtained and that the fit model could generalize fairly well to unseen images.

University of Macau / Faculty of Science and Technology. / Department of Civil and Environmental Engineering

Sustainable Built Environments Senior Capstone Project / This research examines the viability of tire masonry units as a material for exterior walls in residential construction when compared to other alternative materials (straw bales) and traditional materials and methods (wood frame construction). This comparison is executed via a matrix which assigns scores to each material based on their performance in the following criteria; energy efficiency, human health, environmental health, structural soundness, and monetary costs. Tire masonry units have been offered up as a solution to both tire disposal issues that are detrimental to the environment and the problems posed by the need for virgin materials in housing construction. This research concludes this is not the case, and the use of tire masonry units fails to provide solutions for either of these pressing issues.

No description available.

In order to provide data for non-rolling tire models that are used in computer simulations of vehicle dynamics, a tire test rig is designed and manufactured which attaches to an MTS kinematics and compliance machine. This test rig is developed for the purpose of characterizing the loaded radius, overturning moment, and displacement of multiple tires in the vertical, lateral, and longitudinal test axes. Equations are developed and used to fit these parameters for the purpose of representing them in non-rolling vehicle simulation models. / Master of Science

Commercial tyre maintenance outsourcing is a creative and innovative service offering to the road freight industry in South Africa. It allows fleet operators to focus on their core business aspects, leaving the management and control of the tyres in their fleet to professional service providers with the necessary technical expertise and experience in this field. Currently tyre maintenance outsourcing service providers are under increasing pressure mainly due to price wars in the marketplace between the major tyre manufacturers fighting to maintain or increase their market share. The road freight industry in South Africa is also unique in that there is a hand full of major players, dominating more than fifty percent of the market, thereby leaving tyre suppliers and service providers doing everything in their power to retain the business they do have, and aiming to increase their share of the market at any cost. The main objective and purpose of this study has therefore been to conduct an investigation into commercial tyre maintenance outsourcing practises in South Africa. The following aspects were covered in this study: ! Defining the concept of outsourcing and more specifically tyre maintenance outsourcing. ! An overview of the tyre maintenance services currently available in the South African market and possible alternatives that may appear in the future. ! The current state of the commercial tyre industry in South Africa, focusing on the main role players and the services and products they offer to the market. ! The current state of the road freight industry in South Africa, focusing on the market shares the main role players hold, and other relevant transport statistics. ! The factors that play a role in the calculation of cost per kilometre rates, as well as the aspects which contribute to the success of a tyre maintenance outsourcing contract. ! An evaluation of the implications of technological advances on tyre maintenance outsourcing. Synopsis - ii Based on the above, a number of recommendations were made firstly (i) for companies that are current or potential users of tyre maintenance outsourcing, and secondly (ii) for companies that are current or potential providers of tyre maintenance outsourcing. (i) Recommendations for tyre maintenance outsourcing users 1. Companies need to identify their core and non-core activities. 2. Potential outsourcing users need to identify the most appropriate service provider not on pricing alone, but should also consider the overall long term business relationship, as well as the total service package on offer. 3. Companies need to realise that outsourcing is not a short-term solution to control costs, but a long-term project where the true benefits will take time to materialize. 4. Companies need to ensure that a clear tyre policy is agreed upon with the service provider at the inception of the contract. 5. Companies need to ensure that a service level agreement with measurable key performance indicators (KPI’s) is agreed upon with the service provider at the inception of the contract. 6. Companies need to understand the full cost of all the different items associated with the contract they are entering into. (ii) Recommendations for tyre maintenance outsourcing service providers 1. Companies need to build excellent relationships with their clients as to increase communication and flow of information. 2. Companies need to analyse the service they currently provide and determine which factors must be improved upon as to increase their service levels and competitiveness in the marketplace. 3. Companies need to carefully verify all the information they receive from fleet operators upon quoting for a new contract. 4. Companies need to understand the needs of the market they operate in, as to adapt their service offerings around these needs. / Prof. J.H. du Plessis