This thesis research has attempted to address two challenging problems in winter road maintenance, namely road surface condition (RSC) estimation and forecasting. For RSC estimation, the goal of the research was to develop models to discriminate RSC classes based on continuous friction measurements (CFM) and other available data such as temperature and precipitation history. A systematic exploratory study was conducted on an extensive field data set to identify the categorical relationship between RSC and various aggregate CFM measures, such as those related to probability distribution and spatial correlation. A new multi-level model structure was designed, under which binary logistic regression models were calibrated and validated utilizing several carefully chosen aggregate measures to classify major RSC types. This model structure was found to be effective in capturing the overlapping nature of CFM ranges over different RSC types -- a problem which has not been addressed adequately in the past studies. An alternative model with support vector machine (SVM) was also developed for benchmarking the performance of the proposed logit model. It was found that the two types of models are comparative in performance, confirming the high performance of the proposed multi-level model. For road surface condition forecasting, a novel conceptual framework for short-term road surface condition forecasting is proposed, under which the short-term changing process of surface temperature, friction level and contaminant layer depths, is comprehensively explored and analyzed. This study framework is designed to consider all important conditional factors, including weather, traffic and maintenance operations. The maintenance operations, especially salting, are handled by loosening the strict Markovian assumption, i.e., a history instead of one single time interval of salting operations is considered. In this way, the variation of snow/ice melting speed caused by both residual salt amounts and salt/contaminant mixing states is incorporated in the forecasting model, which enables accurate short-term forecasting for contaminant layers. This approach practically circumvents a major limitation of previous studies, making the post-salting RSC forecasting more reliable and accurate. Under the proposed model framework, several advanced time series modelling methodologies are introduced into the analysis, which can capture the highly complex interactions between RSC measures and conditional factors simultaneously. Those methodologies, especially the univariate and multivariate ARIMA methods, are for the first time applied to the winter RSC evolution process. The forecasting errors of surface temperature, friction level and contaminant layer depths are all found to be small, implying that both the proposed study framework and the resulting solutions closely match the real-world observations. The proposed forecasting models are simple in structure, easy to interpret and mostly consistent with physical knowledge. Compared to the existing models, the proposed models provide extra flexibility for refactory, tuning and deployment. Furthermore, all the modelled RSC measures are numerical and the forecast errors are relatively small, suggesting empirical models could be an efficient alternative to physical models. With the well-designed modelling methods, the resulting empirical models as calibrated in our study can be implemented into a decision support and simulation tool with high temporal resolution and accuracy.

Made available in DSpace on 2014-06-11T19:24:40Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-02-05Bitstream added on 2014-06-13T18:52:25Z : No. of bitstreams: 1 masiero_fc_me_botfca.pdf: 638059 bytes, checksum: abfe7790012d582df70c55bce95376dd (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O trator agrícola é a principal fonte de potência utilizada na agricultura e a maioria dos novos modelos disponíveis no mercado apresenta tração dianteira auxiliar (TDA). A preferência pelos tratores com tração dianteira auxiliar é devido à sua maior capacidade de tração, principalmente em condições trativas adversas e, sobretudo pela relação benefício e custo ser positiva e maior que os outros modelos. Esse trabalho foi realizado com o objetivo de avaliar o rendimento dinâmico na barra de tração de tratores agrícolas com tração dianteira auxiliar (4x2 TDA) em diferentes condições de superfície trativa comparando-os com os valores teóricos e práticos da bibliografia (“Fator 0,86” de Wendel Bowers e norma D497.4 ASAE, 1999) e determinar o rendimento dinâmico na barra para a superfície de solo com cobertura vegetal, pois existe pouca bibliografia e é uma realidade no Brasil com o plantio direto na palha. Avaliaram-se onze tratores agrícolas em diversas condições de ensaio de campo e condições de superfície, variando-se o tipo construtivo e modelos de conjunto de pneus, pressões de inflação dos pneus, relações entre o peso e potência do motor e velocidade teórica de deslocamento. Os dados de rendimento máximo na barra de tração do trator obtidos nos ensaios foram arranjados em grupos, obtendo-se o rendimento dinâmico médio na barra de tração e desvio padrão para cada condição de superfície. Foram coletados os dados para o cálculo do rendimento na barra de tração do trator, velocidade de deslocamento, patinagem das rodas dianteiras e traseiras do trator, consumo de combustível, força de tração e potência disponível na barra de tração.a realização do experimento, utilizou-se a Unidade Móvel de Ensaio... / The agricultural tractor is the main power source used in the agriculture and the most of available new tractor models in the marketing present auxiliary front drive (4WD). The preference for the 4WD tractors is due to biggest traction capacity, mainly in adverse tractive conditions and, mainly for the relationship benefit and cost to be positive and larger than the other models. This research was accomplished with the objective to evaluate the dynamic drawbar performance of several agricultural tractors 4WD in different surface condition (concrete, firm soil and tilled soil) comparing them with the theoretical and practical values of the bibliography (Wendel Bowers 0.86 Factor and D497.4 ASAE standard, 1999) and to determine the dynamic drawbar performance for the soil surface with vegetable covering, that doesn't exist in the bibliography and it is a reality in Brazil with the minimum cultivate. Eleven agricultural tractors were evaluated all 4WD in several field test conditions and surface conditions, being varied the tire constructive type and models, tire inflation pressures, relationships between the weight and engine power and forward speed. The maximum tractor drawbar performance obtained in the tests was arranged in groups, being obtained the medium dynamic drawbar... (Complete abstract click electronic access below)

<p>Changes to the surface condition of a grinding wheel caused by excessive wear can result in geometric inaccuracy and severe thermal damage to a workpiece. As a precision metal removal process, grinding is typically a finishing operation and such errors are costly in both materials and lost time. Unfortunately grinding wheel performance is difficult to predict, and workpiece damage is commonly prevented by frequent dressing of the wheel surface. However, such over dressing is also costly in unnecessary machine down time and consumption of the grinding wheel. Monitoring systems have been developed in an effort to prevent damage to the workpiece and unnecessary dressing, but various difficulties have prevented any single system from achieving widespread application.</p> <p>The following body of research focuses on the investigation and development of a pneumatic sensor for monitoring the surface condition of a grinding wheel. These sensors are relatively simple, robust and inexpensive, and well suited to in situ applications. While these sensors are traditionally used to measure displacement of static or quasi-static surfaces, research into dynamic applications has shown they can detect the features or topography of a moving surface. Inspired by these developments, a monitoring method employing both the static and dynamic measurement capabilities of the sensor is proposed with applications to both metal-bonded and vitrified grinding wheels.</p> / Master of Applied Science (MASc)

The hot forming-quenching (HFQ) process has introduced grains and subgrain growth, accompanied with modification of the intermetallic particle distribution in AZ31 magnesium alloys. Each region of the HFQ component represents significant grain structure variation and surface conditions that contributed to the corrosion susceptibility. The homogeneous grain structure significantly ruled the corrosion propagation features by filiform-like corrosion. Immersion of AZ31 alloys in 3.5 wt.% NaCl indicated higher corrosion rate of HFQ TRC (corrosion rate: 10.129 mm/year), a factor of 10 times, higher than the rolled alloy (corrosion rate: 0.853 mm/year) and a factor of 2 times, higher than the corrosion rate of MCTRC alloy (corrosion rate: 5.956 mm/year). Much lower corrosion rate was indicated in the as-cast TRC and MCTRC alloys, compared to the alloys after HFQ process that revealed the contribution of network or continuous distribution of β-Mg17Al12 phase particles to reduce the corrosion driven in chloride solution. In contrast, discontinuous distribution of cathodic β-Mg17Al12 phase particles increases the corrosion rate of HFQ TRC alloy by promoting the cathodic reaction and intense filament propagation resembling the coarse interdendritic and grain boundaries attack. The presence of high population densities of cathodic Al8Mn5 particles in HFQ rolled AZ31B-H24 alloy significantly reduced the corrosion driven for intense corrosion attack on the rolled alloy. The surface preparation by mechanical grinding process induced MgO and Zn-enrichment layer, accompanied with near surface deformed layer that consisted of nanograins in the range size of 40 to 250 nm. The grinding process refined the surface by removing the cutting damage and marks that formed during the thermomechanical process and led to stable potential of the HFQ AZ31 alloys, in the range of -1.59 to -1.57 V, during open circuit potential (OCP) measurement. The surface regularity with grinding path causing the filament to propagate following the grinding direction. The as-received surface contained many cutting damages and deep scratch marks from the rolling and casting processes that could introduce many corrosion initiation sites. The absence of the grinding direction on the as-received surface could control intense corrosion susceptibility, due to the non-linear filament propagation. The surface irregularity on chromic acid cleaned surface of HFQ rolled AZ31B-H24 alloy also contributed to low corrosion potential of the rolled alloy during OCP and potentiodynamic polarization measurement.

No description available.

Following development of rectangular prestressed, precast concrete panels (PCP) that could be used as stay-in-place formwork adjacent to expansion joints in bridge decks, the Texas Department of Transportation (TxDOT) initiated a research effort to investigate the use of PCP units at skewed expansion joints. The fabrication of trapezoidal PCP units was studied and the response of skewed panels with 45° and 30° skew angles was obtained. The panels were topped with a 4 in. thick cast-in-place (CIP) slab to complete the bridge deck. Specimens with 45° skew performed well under service and overload levels. The deck failed in diagonal shear at loads well over the design level loads. However, two 30° specimens failed prematurely by delamination between the topping slab and the PCP. The cause of the delamination was insufficient shear transfer capacity between the PCP and CIP topping slab. For the specimens tested at a square end, the failure mode was punching shear at high loads for all specimens. The surface condition of the PCP was specified to have a “broom finish” and the panel was to have a saturated surface dry (SSD) condition so that PCP units would not leach moisture from the CIP topping slab. Neither of these conditions was satisfied in the two panels that failed prematurely. Although the panels were specified to have a broom finish, the panel surface had regions that were quite smooth. The objective of this research project was to reinvestigate the response of 30° PCP at an expansion joint following specified procedures for finish and moisture conditions. One specimen was constructed with a rectangular panel placed between two 30° skewed panels. These panels had a much rougher surface texture than the previously tested panels that failed in delamination. The skewed ends of the specimen were subjected to monotonically increasing static loads at midspan of the panel ends. The panels failed in diagonal shear and the response of the tested specimen confirmed that the panel surface roughness, and not the skew angle, caused delamination with the previously tested specimens. While TxDOT does not currently specify a minimum panel surface roughness, a surface roughness of approximately 1/4 in. is required in some codes for developing composite action. In addition, wetting the panels to a SSD condition prior to placement of the topping slab further enhances shear transfer between the topping slab and the PCP. / text

Several past studies have attempted to quantify the impact of winter weather conditions on highway mobility in terms of traffic volume, speed, and capacity. While consistent in their general findings, these studies have shown considerably different results in terms of effect size and contributing factors. More importantly, most of these studies have not attempted to model the effects of winter maintenance operations on mobility or isolate these effects from those due to snowstorm characteristics, rendering their results and the proposed methods of limited use for estimating the benefits of maintenance activities. This research attempts to address this gap through a statistical analysis of a data set that is unique in terms of spatial and temporal coverage and data completeness. The data set includes both event based and hourly observations of road weather and surface conditions, maintenance operations, traffic volume and speed, as well as several other measures, from 21 highway sections across the province of Ontario. Event based information is available for six winter seasons (2000 to 2006) at 19 of the sites. For this event based data a matched pair technique was employed to determine the changes in traffic volumes and speeds under matched conditions with and without snow events. A regression analysis was subsequently performed to relate the changes in traffic volume and speed over an event to changes in various contributing factors such as highway type, snow event characteristics and road surface conditions. A case study was conducted to illustrate the application of the developed models for quantifying the mobility impact of road surface condition and the mobility benefit of winter maintenance operations. Complete hourly records were available for all 21 sites for three winter seasons. This was used to perform the evaluation on an hourly basis. A matching technique is employed to assign hour-by-hour median speeds observed under typical weather and road surface conditions to each hour of a snowstorm event. A regression analysis is subsequently performed to relate changes from average hourly speed to various contributing factors such as highway type, weather conditions and maintenance operations. Effects of maintenance operations are represented by an intermediate variable called road surface condition index (RSI). A case study is conducted to illustrate the application of the developed models for quantifying the mobility impact of winter snowstorms and the mobility benefit of maintenance operations. The models developed in these analyses confirmed the relationships between weather variables and traffic volume and speed described in the literature. In addition a strong association between road surface condition and traffic volumes and speed was identified.

No description available.

Orientador: Kléber Pereira Lanças / Banca: Alberto Kazushi Nagaoka / Banca: Paulo Roberto Arbex Silva / Resumo: O trator agrícola é a principal fonte de potência utilizada na agricultura e a maioria dos novos modelos disponíveis no mercado apresenta tração dianteira auxiliar (TDA). A preferência pelos tratores com tração dianteira auxiliar é devido à sua maior capacidade de tração, principalmente em condições trativas adversas e, sobretudo pela relação benefício e custo ser positiva e maior que os outros modelos. Esse trabalho foi realizado com o objetivo de avaliar o rendimento dinâmico na barra de tração de tratores agrícolas com tração dianteira auxiliar (4x2 TDA) em diferentes condições de superfície trativa comparando-os com os valores teóricos e práticos da bibliografia ("Fator 0,86" de Wendel Bowers e norma D497.4 ASAE, 1999) e determinar o rendimento dinâmico na barra para a superfície de solo com cobertura vegetal, pois existe pouca bibliografia e é uma realidade no Brasil com o plantio direto na palha. Avaliaram-se onze tratores agrícolas em diversas condições de ensaio de campo e condições de superfície, variando-se o tipo construtivo e modelos de conjunto de pneus, pressões de inflação dos pneus, relações entre o peso e potência do motor e velocidade teórica de deslocamento. Os dados de rendimento máximo na barra de tração do trator obtidos nos ensaios foram arranjados em grupos, obtendo-se o rendimento dinâmico médio na barra de tração e desvio padrão para cada condição de superfície. Foram coletados os dados para o cálculo do rendimento na barra de tração do trator, velocidade de deslocamento, patinagem das rodas dianteiras e traseiras do trator, consumo de combustível, força de tração e potência disponível na barra de tração.a realização do experimento, utilizou-se a Unidade Móvel de Ensaio... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The agricultural tractor is the main power source used in the agriculture and the most of available new tractor models in the marketing present auxiliary front drive (4WD). The preference for the 4WD tractors is due to biggest traction capacity, mainly in adverse tractive conditions and, mainly for the relationship benefit and cost to be positive and larger than the other models. This research was accomplished with the objective to evaluate the dynamic drawbar performance of several agricultural tractors 4WD in different surface condition (concrete, firm soil and tilled soil) comparing them with the theoretical and practical values of the bibliography (Wendel Bowers "0.86 Factor" and D497.4 ASAE standard, 1999) and to determine the dynamic drawbar performance for the soil surface with vegetable covering, that doesn't exist in the bibliography and it is a reality in Brazil with the minimum cultivate. Eleven agricultural tractors were evaluated all 4WD in several field test conditions and surface conditions, being varied the tire constructive type and models, tire inflation pressures, relationships between the weight and engine power and forward speed. The maximum tractor drawbar performance obtained in the tests was arranged in groups, being obtained the medium dynamic drawbar... (Complete abstract click electronic access below) / Mestre

The thesis deals with machining of rotating parts made from hardened steel. The introductory chapter describes the problems of turning and grinding. The next chapter deals with heat treatment and machined materials. The next lists the used cutting materials. Criteria for evaluating the quality of the surface. A selection of cutting materials for the machining of hardened steels from selected manufacturers. The final chapter is a comparison of the described technologies.