Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2009. / Full text also available online. Scroll down for electronic link.

Made available in DSpace on 2014-06-11T19:31:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2001-02-05Bitstream added on 2014-06-13T20:22:38Z : No. of bitstreams: 1 nagaoka_ak_dr_botfca.pdf: 2279820 bytes, checksum: 149eef5c845342281d3c5d15503e3456 (MD5) / 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... / 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)

The objective of this thesis was to estimate the rate at which four types of farm machinery lose value in Canada. Specifically, Canadian data on used machinery prices was utilized to produce estimates of economic depreciation for two-wheel-drive tractors, combines, square balers and large round balers. The data used in this thesis to make these estimates are special for two reasons. First of all, they represent the only extensive record of Canadian used farm equipment prices available. Most previous studies have based their estimates on American data, assuming that they apply equally well to the Canadian situation. Secondly, these data record actual transactions in the used market and these transactions have been reported in an unaveraged format. This is valuable because information on options, horsepower, condition, and, most importantly, hours of use was retained for each machine. The availability of this information permitted richer and more specific estimates of depreciation. In particular, the inclusion of hours of use in the models enabled a distinction to be made in this thesis between the component of depreciation which is directly attributable to age and that component which is directly attributable to accumulated hours of use. It is felt that this distinction provides a beginning point for the study of depreciation due to simple "wear and tear", and that depreciation which is due to obsolescence and technological change. As well, this thesis extensively reviewed the literature on depreciation in an effort to determine the best approach to follow. The method finally adopted was the "remaining value approach"; however, the thesis went further than the typical remaining value approach because an attempt was made to estimate the pattern as well as the rate of depreciation. This was done by initially adopting a functional form which was flexible enough to let the data "choose for themselves" between the commonly used depreciation rules of thumb (declining balance, straight-line and one-hoss-shay patterns). This was possible by using the Box-Tidwell procedure. This Box-Tidwell procedure when applied to the extensive tractor data indicated that tractors in Canada follow a declining balance (geometric) pattern of depreciation. This was taken as support for the adoption of semi-log models to estimate depreciation. The main findings of this thesis are, first, that depreciation rates vary among assets (from approximately 9% for tractors to nearly 16% for large round balers), and, secondly, that these rates are less than those allowed by the government for tax purposes. It was concluded that this generosity on the part of the government would be acceptable if it applied equally to all depreciable assets, but the divergence in depreciation rates found in this thesis indicate that generous blanket depreciation charges give more advantage to some than to others. / Land and Food Systems, Faculty of / Graduate

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Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 260-273).

Call number: LD2668 .T4 1960 H35