Made available in DSpace on 2014-06-11T19:31:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-07-05Bitstream added on 2014-06-13T20:02:16Z : No. of bitstreams: 1 monteiro_la_dr_botfca.pdf: 626311 bytes, checksum: bc13faf71eca1d35de66ac8b6e656b7b (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O trator agrícola é uma das principais fontes de potência no meio rural. A utilização correta dos pneus, tanto em relação ao seu tipo quanto à calibração de sua pressão interna, são fatores que influenciam, significativamente, no seu desempenho. Outros fatores de regulagem do trator, tais como, a lastragem e a velocidade de deslocamento ideal para cada condição de superfície de solo, são fatores que modificam sua eficiência trativa. Neste trabalha avaliou-se o desempenho operacional e energético de dois tratores agrícolas 4x2 TDA com potência nominal no motor de 132 kW (180 cv), através do consumo horário e específico de combustível, patinagem, rendimento e potência na barra de tração em pista de concreto e em pista de solo agrícola, segundo a norma OECD – Code 2 (2008), para três velocidades teóricas de deslocamento do trator 6,5 km.h-1 , 7,5 km.h-1 e 8,5 km.h-1, correspondentes às marchas B2, B3 e C1 marcadas no painel dos tratores . Aplicou-se um delineamento experimental em faixas, denominadas pistas, e definidas pelas condições da superfície de rolamento (Concreto e Solo Agrícola). Em cada pista foram dispostos os tratamentos com um arranjo fatorial de 2x2x3, sendo analisados dois tratores (John Deere1 e New Holland), o tipo de superfície de rolamento (pista de concreto e pista de solo agrícola) e as marchas utilizadas nos tratores ensaiados (B1, B2 e C1), com cinco repetições por faixa, totalizando 60 unidades experimentais. Esses fatores foram arranjados para permitir a avaliação dos efeitos das variáveis individualmente ou em grupos, sendo todos os dados submetidos... / The tractor is a major energy and work source in rural areas. The correct use of tires, both in relation to their type and the calibration of its internal pressure, are factors that significantly affect the performance. Other factors that modify traction efficiency are related to the tractor setup, such as the ballast (weight balance) and the ideal travel speed for each soil condition. In this work the operational and energy performance of two agricultural tractors with 132 kW (180 hp) of engine rated power were evaluated based on data of efficiency and power in the drawbar, fuel consumption, specific fuel consumption and tire slippage. The tests were run on concrete runway, according to the standard OECD - Code 2, as well as in agricultural runway with the same three theoretical speeds of the tractor: 6,5 km.h-1, 7,5 km.h-1 and 8.5 km.h-1, which correspond to gears B2, B3 and C1, respectively. An experimental design in bands was utilized, where each band corresponded to one of two conditions of the soil surface (concrete and agricultural soil), with three travel speeds and five replicates. Thus, 120 experimental units were conduced and the experimental data was treated trough basic descriptive statistics and analysis of variance. A Mobile Unit Drawbar Tests – UMEB was used in the experiments at the Nucleus of Agricultural and Forest Machinery and Tire Tests - NEMPA, Department of Agricultural Engineering, Faculty of Agricultural Sciences - FCA - UNESP, Botucatu – SP. This unit was operated like a dynamometric car (or braking car), equipped with a data acquisition and storage system to manage the signals generated by the sensors on the tractor and UMEB. The ambient temperature, relative humidity, and temperature of the fuel were monitored. Two flow meters were used to measure fuel consumption; one assembled... (Complete abstract click electronic access below)

Les procédés de mise en forme des tôles minces sont largement utilisés dans l'industrie. L’utilisation optimale des alliages légers ou des aciers à haute résistance, propices à des économies d’énergie dans le domaine des transports, nécessite une connaissance approfondie de leurs limites de formabilité. Classiquement, la formabilité d’une tôle est caractérisée par l’apparition d’une striction localisée. Cependant, pour des chargements spécifiques (chemins de déformation complexes ...), la rupture caractérise la formabilité du matériau, la courbe limite de formage à rupture (CLFR) plutôt que celle à striction (CLFS) doit alors être considérée. Pour identifier la CLFS et la CLFR pour des chemins de déformation linéaires et non-linéaires, les méthodes conventionnelles requièrent différents dispositifs expérimentaux et différentes formes d'éprouvette pour atteindre une large gamme de chemins de déformation. L'essai de traction biaxiale, associé à une éprouvette cruciforme, est possible pour la réaliser. De plus, le changement de chemin est activé au cours de l’essai, sans déchargement. Le premier objectif de cette étude est de montrer que l'essai de traction biaxiale, associé à une forme unique d'éprouvette cruciforme, permet de tracer la CLFS et la CLFR pour plusieurs chemins de déformation, qu’ils soient linéaires ou non-linéaires. En premier lieu, des essais ont été réalisés sur des tôles d’alliage d’aluminium 5086 (épaisseur initiale de 4 mm) à partir d’une forme d’éprouvette déjà proposée au laboratoire. Une nouvelle forme d'éprouvette cruciforme a été proposée pour des tôles moins épaisses (2 mm), plus répandues. Cet éprouvette a été validée pour étudier la formabilité d’un acier dual phase DP600 pour plusieurs chemins de déformation. Le deuxième objectif est de discuter la validité de critères classiques de rupture ductile. Pour les deux matériaux, un critère a finalement été identifié pour prédire assez précisément les résultats expérimentaux. / Sheet metal forming is very common in industry for producing various components. The optimal use of light alloys or high strength steels in transportation for energy economy, requires in-depth analysis of their formability. Usually, the formability of sheet metal is controlled by the onset of localized necking. However, under specific loadings (complex strain paths...), fracture characterizes the formability and the forming limit curve at fracture (FLCF) instead of the forming limit curve at necking (FLCN) should be considered. For identifying FLCN and FLCF under linear and non-linear strain paths, conventional methods require different experimental devices and geometrical specifications of specimen to cover a wide range of strain paths. However, using the in-plane biaxial tensile test with just one shape of cruciform is sufficient for that, even changes of strain path without unloading can be made during the test. The first objective of this study is to show that the in-plane biaxial tensile test with a single type of cruciform specimen permits to investigate the FLCN and FLCF of sheet metals under different linear and non-linear strain paths. Firstly, the forming limit strains at fracture of AA5086 sheet (t=4 mm) under linear and non-linear strain paths have been characterized, by testing an existed dedicated cruciform specimen. Thinner sheet metals are often used in industry, so a new shape of cruciform specimen with an original thickness of 2 mm was proposed. This specimen is successfully used to investigate the formability of DP600 sheet under linear and two types of non-linear strain paths. The second objective is to discuss the validity of commonly used ductile fracture criteria to predict the onset of fracture. Some ductile fracture criteria were used to produce numerical FLCFs for AA5086 and DP600 sheet. Finally, for the two tested materials, it is possible to find a criterion to predict the experimental FLCFs for either linear or non-linear strain paths.

Orientador: Kléber Pereira Lanças / Banca: Saulo Philipe Sebastião Guerra / Banca: Paulo Roberto Arbex Silva / Banca: Renildo Luiz Mion / Banca: Alberto Kazushi Nagaoka / Resumo: O trator agrícola é uma das principais fontes de potência no meio rural. A utilização correta dos pneus, tanto em relação ao seu tipo quanto à calibração de sua pressão interna, são fatores que influenciam, significativamente, no seu desempenho. Outros fatores de regulagem do trator, tais como, a lastragem e a velocidade de deslocamento ideal para cada condição de superfície de solo, são fatores que modificam sua eficiência trativa. Neste trabalha avaliou-se o desempenho operacional e energético de dois tratores agrícolas 4x2 TDA com potência nominal no motor de 132 kW (180 cv), através do consumo horário e específico de combustível, patinagem, rendimento e potência na barra de tração em pista de concreto e em pista de solo agrícola, segundo a norma OECD - Code 2 (2008), para três velocidades teóricas de deslocamento do trator 6,5 km.h-1 , 7,5 km.h-1 e 8,5 km.h-1, correspondentes às marchas B2, B3 e C1 marcadas no painel dos tratores . Aplicou-se um delineamento experimental em faixas, denominadas pistas, e definidas pelas condições da superfície de rolamento (Concreto e Solo Agrícola). Em cada pista foram dispostos os tratamentos com um arranjo fatorial de 2x2x3, sendo analisados dois tratores (John Deere1 e New Holland), o tipo de superfície de rolamento (pista de concreto e pista de solo agrícola) e as marchas utilizadas nos tratores ensaiados (B1, B2 e C1), com cinco repetições por faixa, totalizando 60 unidades experimentais. Esses fatores foram arranjados para permitir a avaliação dos efeitos das variáveis individualmente ou em grupos, sendo todos os dados submetidos... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The tractor is a major energy and work source in rural areas. The correct use of tires, both in relation to their type and the calibration of its internal pressure, are factors that significantly affect the performance. Other factors that modify traction efficiency are related to the tractor setup, such as the ballast (weight balance) and the ideal travel speed for each soil condition. In this work the operational and energy performance of two agricultural tractors with 132 kW (180 hp) of engine rated power were evaluated based on data of efficiency and power in the drawbar, fuel consumption, specific fuel consumption and tire slippage. The tests were run on concrete runway, according to the standard OECD - Code 2, as well as in agricultural runway with the same three theoretical speeds of the tractor: 6,5 km.h-1, 7,5 km.h-1 and 8.5 km.h-1, which correspond to gears B2, B3 and C1, respectively. An experimental design in bands was utilized, where each band corresponded to one of two conditions of the soil surface (concrete and agricultural soil), with three travel speeds and five replicates. Thus, 120 experimental units were conduced and the experimental data was treated trough basic descriptive statistics and analysis of variance. A Mobile Unit Drawbar Tests - UMEB was used in the experiments at the Nucleus of Agricultural and Forest Machinery and Tire Tests - NEMPA, Department of Agricultural Engineering, Faculty of Agricultural Sciences - FCA - UNESP, Botucatu - SP. This unit was operated like a dynamometric car (or braking car), equipped with a data acquisition and storage system to manage the signals generated by the sensors on the tractor and UMEB. The ambient temperature, relative humidity, and temperature of the fuel were monitored. Two flow meters were used to measure fuel consumption; one assembled... (Complete abstract click electronic access below) / Doutor

Dissertation submitted in compliance with the requirement for a Master's Degree in Technology: Chiropractic, Technikon Natal, 1996. / The purpose of this study was to compare the effects of McMannis traction and Intermittent traction, both m conjunction with chiropractic manipulation in the treatment of chronic i.e. longer than four weeks, mechanical lower back pain. It was hypothesised by the author that McMannis traction would be the traction treatment of choice, as it enables the joints of the lumbar vertebrae to be moved through their normal anatomical range of motion while being traeticned axially. In addition this type of traction is more specific and allows the therapist to determine the amount of traction that is being applied to the patient because it is being applied manually. Intermittent traction on the other hand is a motorised non-specific traction and affects several joints at one time (Saunders 1979). / M

M.Tech. (Chiropractic) / Purpose: The purpose of this randomised comparative study was to establish the effects which these modalities had on pain perception and range of motion in patients with acute cervical facet syndrome. This was done by comparing manual cervical spine traction alone; to cervical spine adjustments alone to manual cervical spine traction applied post cervical spine adjustments. Method: A total of 30 participants were recruited for this study by placing advertisements in and around the University of Johannesburg, Doornfontein Campus. Participants had to meet the requirements of the inclusion criteria and were excluded if they were found to be unfit for this particular study. The 30 participants were asked to draw a number out of a bag which therefor randomly divided them into three groups of 10 participants each. Procedure: Participants in group A received manual cervical traction alone as their treatment. Participants in group B received cervical spine adjustments alone as their treatment. Finally, participants in group C were treated by performing manual cervical spine traction after the cervical spine adjustment. Each participant was treated a total of six times over a two week period. Measurements were taken on the first, fourth and a seventh consultation. Results: Regarding the Subjective readings, there was an improvement with regards to the Numerical Pain Rating Scale values for all three groups, but the combination group of manual cervical spine traction performed post cervical spine adjustment, showed the greatest improvement over the trial period on intra-group analysis. No statistical significant changes were found on inter group analysis. There was an improvement in Neck Pain Disability Index values for all three groups, but the cervical spine adjustment group showed the greatest improvement over the trial period on intra-group analysis. No statistical significant changes were found on inter group analysis. Regarding the Objective readings, there was an improvement in pressure algometer readings for all three groups, but the cervical spine adjustment group showed the greatest improvement over the trial period on intra-group analysis. No statistical significant changes were found on inter group analysis. There was an improvement in Cervical Range of Motion readings for all three groups, but the combination group of manual cervical spine traction performed post cervical spine adjustment showed the greatest improvement for flexion, extension and bilateral rotation on intra-group analysis. However, for bilateral lateral flexion, the cervical spine adjustment group showed the greatest improvement on intra group analysis. No statistical significant changes were found on inter group analysis. Conclusion: There were clinically significant improvements within each of the three groups on intra group analysis but no clinically significant differences were found on inter group analysis. Therefore, none of the groups could be singled out as being the best treatment approach for acute cervical facet syndrome. With regards to the Chiropractic profession the outcome of this study therefore suggests, that the chiropractic adjustment alone is sufficient in treatment of acute cervical facet syndrome as none of the groups proved to be superior.

Vitreomacular traction (VMT) is a condition characterized by an incomplete posterior vitreous detachment resulting in traction on the macula and decreased visual acuity. The process of vitreomacular traction can lead to a number of maculopathies including cystoid macular edema, epiretinal membranes, and macular holes. VMT is more common in patients over 40 years of age; however no population-based studies documenting the prevalence of VMT in this age group has been published. Purpose: The current study was undertaken to evaluate the prevalence of vitreomacular traction syndrome in the population aged above 40. Clinical examination does not adequately illustrate the extent of vitreomacular adhesion; therefore, Optical Coherence Tomography (OCT) was used to determine the presence of VMT. High-definition OCT has provided new insight into vitreomacular traction syndrome by allowing for better visualization of the tractional forces at the vitreoretinal interface. This investigation will analyze the vitreomacular interface with regard to VMT in correlation to age through use of the Spectral Domain OCT. Methods: One hundred and thirty-one eyes of 67 patients (36 females/31 males) were examined by optical coherence tomography (OCT). OCT was performed to obtain high-resolution cross-sectional images of the vitreoretinal interface in the posterior fundus. Results: The status of the posterior vitreoretinal interface was evaluated as follows; (1) Intact Vitreous- No posterior vitreous abnormality is depicted on OCT. (2) Vitreomacular adhesion/incomplete PVD- the posterior vitreous is partially attached and can be seen in contact with the macula on OCT. (3) Vitreomacular traction- the posterior vitreous is partially adhered to the inner retina resulting in distortion of the retinal architecture. (4) Complete posterior vitreous detachment, indicating no contact between the vitreous and retina. Conclusion: OCT results found no vitreous abnormality in 39.7% of all eyes; PVD in 6.87% of eyes, VMA in 51.1% of eyes, and VMT in 2.29% of eyes. Age was a significant risk factor to the development of VMT, while gender was not. As age increases, the probability of having VMT increases by 1.2%. Due to the association between vitreomacular traction and a variety of maculopathies, recognition and diagnosis of this entity is crucial. High definition OCT has allowed for outstanding visualization of the vitreomacular interface, which has allowed for a better understanding of this entity.

Modern hybrid electric and pure electric vehicles are highly dependent on control algorithms to provide seamless safe and reliable operation under any driving condition, regardless of driver behavior. Three unique and independently operating supervisory control algorithms are introduced to improve reliability and vehicle performance on a series-hybrid electric vehicle with an all-wheel drive all-electric drivetrain. All three algorithms dynamically control or limit the amount of torque that can be delivered to the wheels through an all-electric drivetrain, consisting of two independently controlled brushless-direct current (BLDC) electric machines. Each algorithm was developed and validated following a standard iterative engineering development process which places a heavy emphasis on modeling and simulation to validate the algorithms before they are tested on the physical system. A comparison of simulated and in-vehicle test results is presented, emphasizing the importance of modeling and simulation in the design process.

No description available.

This thesis characterizes the transient thermal response of a 12/16 External Rotor Switched Reluctance Machine (ERSRM) for an E-bike application. A method for calculating coil capacitance based on machine design parameters was introduced and implemented into a standard commercial Lumped Parameter Thermal Network (LPTN). A sizing criterion was proposed for the cuboid number in a physically accurate LPTN coil model design. This sizing criterion considers the change in model size with motor speed or forced convection. The LPTN with a more accurate calculation of capacitance within the coil and a known number of cuboids in the coil was validated with experimental results. An analytical proof was provided that a small number of capacitances is not sufficient to model a typical power-dense coil design. The validated model was used to study the impact of a more accurate capacitance calculation method on motor temperature. Both overload and rated operation were investigated. During overload conditions, it was found that the standard capacitance calculation from commercial software massively underestimated the heating rate and peak temperature of the coil hot spot, even with the same number of cuboids. The capacitance of the rest of the motor was able to be varied and investigated for its effects on cooldown dynamics. It was found that for short-time transients the coil could be assumed to act adiabatically in this operating range. Operating points across the operating envelope for the motor under study were mapped to determine the region where the adiabatic assumption could be made. It was shown that a transition occurred where the adiabatic assumption ceases to be valid. / Thesis / Doctor of Philosophy (PhD) / This thesis deals with the thermal modelling of electric machines for traction applications using lumped parameter thermal modelling. A novel approach is presented for calculating and distributing thermal capacitance in motor coils. A 12/16 External Rotor Switched Reluctance Motor is characterized based on its transient thermal response and the novel methods proposed are validated. The sizing of a coil-based thermal model is discussed and a criterion for physical validity proposed. The validated model is used in a sensitivity analysis of coil and motor capacitances. For severe overload conditions and short periods, a result is obtained showing the coil can be modelled as adiabatic. Finally, a rated load condition is tested, and a transition is suggested between overload conditions and non-overload conditions.

In this thesis, several design methodologies are presented to improve the reliability of dual traction inverters in hybrid electric vehicles (HEVs). Several power inverter topologies including the two-level voltage-source inverter, the boost voltage-source inverter, the Z-source inverter, and reduced-parts inverters are compared in terms of power ratings, volume, and efficiency. The comparison results show that the two-level voltage-source inverter presents higher efficiency, higher power density, and lower cost. Therefore, the back-to-back two-level voltage-source inverter is selected. DC-link capacitor and power modules are the most vulnerable components in dual traction inverters. The lifetime of capacitor is mainly determined by the core temperature. In this thesis, an interleaving control scheme is proposed to reduce the capacitor power loss by decreasing the total DC-link current harmonics. With reduced capacitor power loss, the core temperature of capacitor is reduced. Therefore, the lifetime of capacitor is improved. In addition, a fast electro-thermal model of traction inverters is proposed to estimate the junction temperatures of power devices. Practical switching losses are measured and thermal coupling effects between multiple devices are considered. The calculation rate of junction temperature is reduced by considering both power loss profiles and properties of the thermal impedance. With this model, over-temperature protection and lifetime evaluation can be implemented to enhance the reliability of traction inverters. Finally, a current sensor fault-tolerant operation scheme with six-phase current reconstruction technique is proposed to improve the reliability of dual inverters. In order to get the missing phase currents, the PWM signals are phase shifted to create the reconstruction conditions. With measured DC-link current, all phase-currents of dual inverters are obtained at the expense of slight degradation of maximum allowable modulation index. Therefore, when some or all of the phase current sensors are failed, the dual traction inverters can operate normally. / Thesis / Doctor of Philosophy (PhD)