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Call number: LD2668 .T4 1978 H48 / Master of Science

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This thesis describes an investigation into the effect of fluid and flow parameters on cavitation dynamics and cavitation erosion. A rotating disc test apparatus was developed fo: dow-type cavitation studies. A vibratory test device was also developed to study the role of cathodic and anodic potentials applied to cavitating bodies. Some major results are given below. Erosion "peaksat about 50°C in water, but under certain conditions material degradation caused by increased corrosion rate cancels out thermodynamic effects at higher temperatures. An erosion peak is also observed as a function of static pressure. Damage increases with velocity until cavitation is fully developed, at which stage the influence of velocity becomes negligible. The changes in erosion zone geometry and mass loss caused by temperature, velocity and pressure variations may be correlated with the effect these parameters have on the cavitation pressure profile. Efforts are described to develop a system for measuring this profile in the rotating disc device. Water quality including dissolved ions, as well as solid and gas impurities, influences both cavitation inception and the amount of cavitation damage caused. The synergism between cavitation erosion and corrosion causes high damage rates in corrosive, cavitating liquids. Solid impurities at medium concentrations may enhance or retard cavitation damage substantially, depending on the physical properties of the solid. Below the saturation level, increasing concentration of dissolved air in water results in a slight decrease in damage, but damage can be almost completely eliminated by the release of air bubbles into the cavitation region. Another important result is that the gas developed by the application of external potentials to a cavitating body provides protection against cavitation erosion through a gas cushioning mechanism. Cathodic protection of cavitating bodies will thus serve to decrease damage rates even in the case of corrosion-resistant materials like stainless / GR 2016

by Lee Yin-sum. / Thesis (M.B.A.)--Chinese University of Hong Kong, 1981. / Bibliography: leaves 55-56.

Orientador: Kléber Pereira Lanças / Banca: Ulisses Rocha Antuniassi / Banca: João Eduardo Guarnetti Santos / Banca: Marcos Milan / Banca: Haroldo Carlos Fernandes / Resumo: O principal objetivo deste trabalho foi desenvolver, instrumentar e avaliar o desempenho de um equipamento para ensaio de pneus agrícolas acoplado a um trator, acionado pela sua tomada de potência, com a finalidade de ensaiar dinâmica e individualmente pneus em condição de campo e avaliar o efeito da passagem do pneu no solo. O equipamento foi desenvolvido no Núcleo de Ensaios de Máquinas e Pneus Agrícolas (NEMPA), pertencente ao Departamento de Engenharia Rural da Faculdade de Ciências Agronômicas da Universidade Estadual Paulista (UNESP), situado no município de Botucatu. Os dados obtidos nas calibrações e nos ensaios foram ajustados pelo método de regressão e os dados do experimento foram analisados considerando-se o delineamento experimental em blocos, no esquema de parcelas subdivididas, tendo nas parcelas os pneus e nas subparcelas as cargas, com cinco repetições. Os valores de índice de cone do solo foram analisados considerando-se o delineamento experimental em blocos, no esquema de parcelas subsubdivididas, e tendo na parcela os pneus, na subparcela as cargas e na subsubparcela as camadas, com cinco repetições. Os resultados do experimento foram interpretados estatisticamente, por meio da análise de variância, adotando-se o nível de significância de 5% e pelo teste de comparação de médias de Tukey. Foram realizados ensaios com variações de velocidades de 0 a 14 km/h, patinagens de 3% a 34%, diâmetros de pneus de 1250 mm a 1722 mm, larguras de pneus de 500 mm a 602 mm e cargas verticais de 5.000 N a 24.000 N. Para estes valores não foram observados danos ao equipamento. O comprimento mais adequado da parcela para os ensaios de campo foi de 20m com freqüência de aquisição de 1Hz. O equipamento permitiu avaliar o desempenho dinâmico de pneus, em condições de solo agrícola, pista asfáltica e comparar diferentes tipos de pneus...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The main objective of this research was to develop, to instrument and to evaluate the performance of a Single Wheel Testing Equipment, linked to a tractor and motioned by the power take off (PTO) with the purpose of dynamically testing individual tires in field and laboratory conditions. The equipment was developed in Agricultural Machinery and Tire Testing Center (NEMPA), Rural Engineering Department of Agronomic Science College, São Paulo State University (UNESP), Botucatu County. The obtained calibration and test data were adjusted using regression method and the experiment data were analyzed considering an experimental design in split plot blocks, with the tire in the parcels and the load tire in the subparcels, with five repetitions. The cone index values were analyzed considering the same experimental design, with the tire in the parcels, the tire load in the subparcels, and the soil layers in the subsubparcels, with five repetitions. The experiment results were statistically interpreted by means of variance analysis, adopting 5% of significance level and using Tukey average test comparison. The tests were realized varying the forward speed from 0 to 14 km/h, the slip from 3% to 34 %, the tire diameter from 1,250 mm to 1,722 mm, the tire width from 500 mm to 602 mm, and the tire loads from 5,000 to 24,000 N. The device worked very well and it was not observed damages or failures for all tested situations. The most adequate parcel length obtained on the field tests was 20 m, using the acquisition frequency of 1 Hz. The equipment permitted to evaluate tire dynamic performance on agricultural field conditions, asphalt track and to compare different tire types as a function of inflation pressure, slip, rolling radius, and tire load. The equipment evaluated individuality the tested tire and have an eletronic date colect system, providing agility and practicity in the tests...(Complete abstract, click electronic access below) / Doutor

Emergency stop controls are essential parts of industrial machinery because they are designed to stop the operation in case of emergencies without risks to operators, equipment, products, or facilities. Current guidelines for emergency stop controls have been formulated based on experience but not on empirical studies. The main objectives of this research were to determine the effects of the type and orientation of emergency stop pushbuttons on the reaction time, mode of activation, and preferences of subjects in order to formulate guidelines for their selection. An experiment consisting of a simple, cooperative assembly operation with a Microbot was designed for this study. The main conclusions of this research are that reaction time to activate emergency stop pushbutton is not affected by the orientation of the control but it is influenced by the type of control. The mode of activation of emergency stop pushbuttons is influenced by both the type and the orientation of the control. Subjects preferred emergency stop pushbuttons without guards or with half guards over controls with full guards, and subjects also preferred an inclined orientation of the control over horizontal or vertical orientations. The following guidelines are recommended for the selection of emergency stop pushbuttons. Select emergency stop pushbuttons without guards. If a guard is absolutely required, select a guard with slots or a half guard to ensure adequate visibility of and access to the button. If possible, give emergency stop pushbuttons an inclined orientation (about 45��) on the control panel. Avoid using vertical orientations for these controls. / Graduation date: 1997

Thesis (Ph. D.)--Landbouwhogeschool te Wageningen, 1983. / Summary also in Dutch. Vita. Includes bibliographical references (p. 287-293).

Thesis (M.S.)--Brigham Young University. Dept. of Physics and Astronomy, 2006. / Includes bibliographical references (p. 67-69).