874 resultados para plastic mulch
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Dissertação de mestrado em Engenharia Industrial
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Dissertação de mestrado integrado em Engenharia e Gestão Industrial
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Dissertação de mestrado integrado em Engenharia e Gestão Industrial
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The effects of tangerine (Phaseolus vulgaris Blanco), lemon (Citrus medica limonum Lush), pear orange (Citrus sinensis L. Osbeck), red copaiba (Copaifera langsdorffii Desf.), rosemary (Baccharis dracunculifolia De Candole), Eucalyptus (Eucalyptus globulus Labillardière and E. citriodora Hook), lemongrass (Cymbopogon citratus Stapf.) and citronella (Cimbopogon nardus Linnaeus) oils at several concentrations on Zabrotes subfasciatus (Boheman) were studied. In toxicity tests, grains of Phaseolus vulgaris L. cv. Rajadinho were impregnated with oils and infested with adults of Z. subfasciatus up to 24 hours old. All tested oils were effective in reducing the viable egg-laying and adult emergence of this pest, in function of the concentrations used, highlighting E. citriodora and E. globulus oils which caused 100% effectiveness from 0.5 mL Kg-1 concentration. In repellency tests, two arenas consisting of plastic containers, connected symmetrically to a central box by two plastic tubes were used. In one of the boxes, untreated beans were placed and on the other ones beans treated with each oil concentration were used. In the central box, five couples of Z. subfasciatus were released. Grains of P. vulgaris treated with oils of E. citriodora, C. citratus and C. oleifera reduced the attraction percentage of Z. subfasciatus adults, while the E. globulus increased this percentage. The percentages of reduced viable eggs ranged from 17.9% (C. medica limonum) to 93.3% (C. nardus), while the reduction on the number of emerged insects was 23.9% and 95.9%, respectively for these same oils.
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Dissertação de mestrado integrado em Engenharia Mecânica
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Density-dependent responses are an important component of the organism life-history, and the resource allocation theory is a central concept to the life-history theory. When resource allocation varies due to environmental changes, a plant may change its morphology or physiology to cope with the new conditions, a process known as phenotypic plasticity. Our study aimed to evaluate how plant density affects Eichhornia crassipes allocation patterns. A total of 214 individuals in high and low density were collected. The density effect was observed in all plant traits examined including biomass accumulation. All traits of E. crassipes demonstrated higher values in high density conditions, except for biomass of leaves. Density exhibited a high influence on vegetative traits of E. crassipes, but did not influence allocation pattern, since a trade-off among the vegetative traits was not found. The morphological plasticity and the absence of trade-offs were discussed as strategies to overcome neighbor plants in competition situations. In high density conditions, there were clear changes in the morphology of the plants which probably allows for their survival in a highly competitive environment.
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Dissertação de mestrado integrado em Engenharia de Materiais
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Dissertação de mestrado integrado em Engenharia Mecânica
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Dissertação de mestrado integrado em Engenharia Mecânica
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Dissertação de mestrado em Engenharia Industrial
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Tese de Doutoramento (Programa Doutoral em Engenharia de Materiais)
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Dissertação de mestrado em Técnicas de Caracterização e Análises Químicas
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Dissertação de mestrado em Ecologia
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Tese de Doutoramento em Engenharia Industrial e de Sistemas.
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This thesis is a continuation of the Enterprise-Ireland Research Innovation Fund (RIF) Project entitled’ "Design and Manufacturing of Customised Maxillo-Facial Prostheses" The primary objective of this Internal Research Development Program (IRDP) project was to investigate two fundamental design changes 1 To incorporate the over-denture abutments directly into the implant. 2 To remove the restraining wings by the addition of screws, which affix the. implant to the dense material of the jawbone. The prosthetic was redesigned using the ANSYS Finite Element Analysis software program and analysed to* • Reduce the internal von Mises stress distribution The new prosthetic had a -63.63 % lower von Mises stress distribution when compared with the original prosthetic. • Examine the screw preload effects. A maximum relative displacement of 22 6 * lO^mm between the bone and screw was determined, which is well below the critical threshold of micromotion which prevents osseointegration • Investigate the prosthetic-bone contact interface. Three models of the screw, prosthesis, and bone, were studied. (Axisymmetnc, quarter volume, and full volume), a recommended preload torque of 0 32 Nm was applied to the prosthetic and a maximum von Mises stress of 1.988 MPa was predicted • Study the overdenture removal forces. This analysis could not be completed because the correct plastic multilinear properties of the denture material could not be established The redesigned prosthetic was successfully manufactured on a 3-axis milling machine with an indexing system The prosthetic was examined for dimensional quality and strength The research established the feasibility of the new design and associated manufacturing method.